TRICKS

1.Wand of negation:
Alot of top players get it no matter what . It's uses are so many and are extremely helpful. For example, it does damage to summoned units. It's quite handy when facing an undead opponent, where you can use it to destroy a pack of skeletons. Other uses include negating that pesky bloodlust, and stopping frenzied abominations from wrecking your troops.

2. Expansions, expansions expansions.
Expanding is one of the most crucial aspects of the game. Knowing where to expand is also very important (i.e. expanding far away from your base where a normal enemy might look, putting an expansion that you can protect close by to your main base.). Another outstanding part of expansions is defending them. It is really quite easy to do, and can be done by making 2-4 tower type buildings (spirt towers, ancient protectors..etc.) near your expansion. For orcs and humans, I advise placing 2 right next to your peon line, to discourage the enemy from terrorizing you with air.

3..When to expand?
This question is really quite huge, and depends on if you can successfully defend your expansion and aren't going to be overwhelmed by the enemy and defeated anytime soon. I advise expanding as soon as possible.. think of it this way, with two gold mines you are increasing your gold production and already have an advantage over your opponent(s). It is very good to have two gold mines fully operational from mid-game on.

4. Creeping
When I first started playing, I thought nothing of leveling my hero(s). Boy was I wrong. You should creep for almost the entire game, even if you have just one hero and no units to back him/her/it up. (Try using moon wells to heal yourself as ne, blight to heal as ud, BM's mirror image for orc, and the archmage's water elementals for humans.) For extensive creeping, you'l' need at least 5 or 6 units to back your hero up. YOU SHOULD RARELY LOSE A UNIT WHILE CREEPING. I'll tell you how in this next section.

5. Micro
A hard yet very worthwhile part of the game to master is micro. That is, controlling each unit to bring it to its fullest potential. For example, having your lich cast frost nova in the heat of a battle, casting bloodlust on your most worthy units, dispelling summoned and negative magic effects with whatever form of abolish magic you have, sleeping starfall, mass teleporting out of a dangerous and fatal situation. It is pretty hard to tell someone how to micro better, its better to lead him or her in the right direction. Heres something that works for me. killing spellcasters or heros that are greatly aiding your opponent first. Once the leader falls, usually the followers will fall too. (Kill a dread lord with a lvl 3 vamp aura and see how much easier it is to kill the ghouls with him.)

6.Battle orders.
This is a topic-overlooked alot. The way you introduce your units to battle is very important. Try having your high hp and heavy damage units up front, your support close behind, and spellcasters in a reasonable position to disable the enemy. Also, try making a balanced army. For example (if you haven't figured it out yet, I play undead a lot.) a mix of abominations, master lvl necromancers, and crypt fiends (with heros) should do just fine against most opposition. but its up to you to adapt to your enemy.

7. Scouting and upgrading
ALWAYS scout your opponent. use whatever you can, shades as undead, owls for night elf, mirror bm images as orc, invisible units as humans. or if you cant do any of these, just send a unit on a suicide mission (preferably one you won't be using anymore). Another overlooked advantage is upgrading. While I cannot tell you what to upgrade, if low on cash, you might look to upgrade the attack of your piercing units, or the defense of your high hp units to serve as better meat shields. If money allows though, I upgrade everything I can get (well almost everything).

8. Be prepared for the worst.
This is really quite simple. All this means is upgrading web so you don't have to do it when you're being swarmed by air and don't even have anti air and crpyt fiends ready yet. It also includes upgrading to magic sentry, increasing the hp of your buildings as humans, getting ensnare as orcs. A good thing to do is to make a bit of air, even if you know your enemy isn't going anti air or air, so even if you lose a battle you still will have air units to harass their army.

STUNT

Area of Effect Stunner:
Mountain King’s thunderclap. Thunder Clap deals good damage around the Mountain King and stuns them for a while. This skill is useful in melee combats against hard hitting uints.

Single Target:
Mountain King’s storm bolt : Deals good damage against single targets with reasonable mana cost. The stunning duration lasts for 2 seconds.
Keeper of the Grove’s Entangle:
This is a skill in which vines pop out of the ground and grab onto the targeted unit. The Wolf Rider’s Ensnare : Although it deals no damage, the ensnared target will not be able to move or attack. In addition to that, any flying ensnared units will be brought down to the ground, rendering the flying unit vulnerable to ground units. This is one of the most useful spells in the game. Crypt Fiend’s Web : Much like the Wolf Rider’s ensnare, but only works against air units. The function of the web is similar to ensnare, but with longer cool down duration. Dread Lord’s Sleep : Need I explain this? Just try to have a nice dream J As you can see, all the races have their share of stunners in the game. There are quite a few reason that stunning is useful : Your units will be allowed to have free hits, selectively targeting / killing the units that are dealing the most damage to your army and catching the retreating opponent.

Free hits:
This one is a no brainer. Stunning or immobilizing units for short period of time could mean the differences between the defeat and victory in small micromanagement-intensive battles. And because Warcraft 3 revolves around these small and frequent battles, the stunning can provide a HUGE boost in your overall effectiveness. The Mountain king’s thunderclap, in this respect, is very abusive at killing off the melee units in early game. With one well-placed thunderclap, you might find yourself claiming victory over the whole game.

Cutting of certain units in the battle:
Stunners are the best way to keeping those annoying spell casters out of the fight. This is especially effective against melee-range units or heroes. In addition to keeping them from inflicting damage on you, you erase the unit’s ability to respond any threats around him / her. This can be abused to extreme with spells like entangle and storm bolt. All you have to do is target the unit that you want out of the picture and they will no longer be able to contribute their power in the battle. For example, lets say you had keeper of the grove with level 3 entangle. You are in the process of fending off those annoying footmen, but you see a mortar team and archmage coming for the support. You can quickly entangle archmage, eliminating any chance of taking damage from blizzard or water elemental. (However, entangle is not a true stunning skill as archmage can still attack cast spells in certain radius. He just can’t move while entangled by the vines) This will allow you to divide the groups of enemies and face them selectively in easier and more digestible amount. Picking off heroes is also an important part of the stunning aspect. At this, Mountaing King excels the most with his stormbolt skill. Stormbolt deals big damage against the heroes and stuns (completely immobilizing) for 2 seconds. While the hero is stunned, he will not be able to cast spells, use items, move or attack. You can use this opportunity to surround that hero and kill it quickly. If your units that are dispatching of the other hero get in trouble, you can simply use your Mountain King’s thunderclap to buy yourself some more time to finish the job.

Stopping the retreating units:
Stuns, especially the area effect stuns can cause a lot of damage to retreating units. Most smart players will retreat their heroes / units when they realize that they are fighting a losing battle. However, with stunning, you can prevent them from running away and finish the job quickly. With single target stuns, you will usually be able to deal damage AND prevent them from running away. This is especially useful against units with large size since if the smaller units around it might not find enough space to go around it. The units then can be easily disposed of. Also, this is ideal for sniping the running heroes with high mobility. Entangle and Stormbolt is the best skill for doing such sniping – while sleep gets the worst stunning skill award (any heroes can be awoken from the attacks from his / her own units as well as enemy units)

OFFENSIVE MANEUVERS

Basic Flanking
An attacking army (or a defending one for that matter) will position itself so that melee units are in the front lines and ranged/caster units are at the rear. This can be exploited by flanking the enemy. Depending on the terrain you may be able to send some units (melee usually) around behind the enemy to attack their more valuable and vulnerable units. By doing this you easily eliminate the ranged/casters and can then overwhelm the enemy’s melee. Don’t use this if you are fighting mainly melee.
Best Races – Night Elf, Orc, and Undead. The sheer speed of ghouls, frenzied units, blood lusted units, and huntresses allows for quick and easy execution of this move. This is also a great aerial maneuver that can be used by all races.
Counters – Run or regroup

Advanced Flanking
Advanced Flanking requires more micro on your part but often yields an easier win. With basic flanking you attack from behind to kill the caster/ranged units. In Advanced Flanking you attack from behind AND all escape routes (ie. direction the enemy can run), leaving the enemy no choice but to stay and die, or Town Portal. As above, if your enemy is mainly melee, don’t do this.
Best Races – Night Elf, Orc, and Undead, for the same reasons as above.
Counters –Town Portal or Mass Teleport (the later can be permanently countered by stunning moves or entangle) are the only ways to escape this.

Ambush
An ambush is a more tactical version of flanking. In this manoeuvre you lure the enemy to where you want them and then strike. In some instances you may know the enemy is about to attack an expansion, allowing you to set up an ambush. Often you will strike while the enemy is still en route to their destination, allowing you to slaughter them easily. This technique is easier to perform if you have good scouting (such as sentinels or owl scouts).
Best Races – Night Elf and Human. The Night Elf can preform this move brilliantly at night due to shadow meld and the speed of their units. If other non-melding units are to be used send them in after the trap has been sprung (dott have the useful ability to fly in mid skirmish). Humans can also perform this to great effect. However, their version is very micro intensive as invisible units will not attack move like melded ones will. This can be overcome with the use of dispel (use it on the invisibility). The humans have the greatest surprise value with this strat as not many people use invisibility for anything other than scouting, a mass teleport target, or to save a unit (usually a hero) from death. All races can execute this move well depending on the terrain. Air units are not as good at ambushes as ground units as the enemy can simply run under them, they can be used for support fire though.
Counters – Invisibility detection or recon. The best cure for this is prevention. If you don’t see it Town Portal or Mass Teleport are the only ways to overcome this move when executed properly. If you try to run most of your units will either die or be very close to dieing, allowing the enemy to counter and kill you.

Spell Ambush
Very Similar to the regular ambush, the spell ambush revolves around a key hero unit casting an area of effect move to kill off the enemy quickly. Other troops should be placed in key locations to stop escape.
Best Races – Night Elf, Human, and (depending on the terrain) Undead. Night Elf and Human can accomplish this strat the same way as they would the regular ambush except by adding blizzard/starfall into the fray. The undead have death and decay, the ultimate offensive spell when the enemy is trapped, which they are. Anti-magic shell will save friendly troops from D & D.
Counters – If you don’t see it coming you will need to Town Portal or Mass Teleport away fast. Don’t bother stunning the hero to stop the spell, you would die if you stayed anyway.

Diversionary Tactics
Diversions are used to lure the enemy away from key positions. To accomplish a diversion you will need a secondary, smaller army. Good ways to use decoys are by making the enemy town portal to an outpost so that you can attack their main base. If they don’t TP they loose their mine.
Best Races – All
Counters – The best counter is to have recon outside your base so you can prepare to meet the main attacking force. Once this is dead (your force will be slightly larger as the enemy had to spilt theirs) you can mop up the troops at your other base and counter. If you don’t have recon you will need to have multiple Town Portal Scrolls or a level 6 Arch Mage. See if the enemy is attacking your outpost with their main hero, if they are not (and you haven’t killed him) it will most likely be a diversion (this can be overcome by the use of mirror image or a wand of illusion so it appears you ARE attacking with your hero).

Russian Roulette
This strategy is mine and mine alone as I am the only person I know of who has done it. In this strat you hit several bases at once, sending your heroes to either the place you want to kill the most, or to individual bases. Before you execute this strat you MUST be sure you have enough troops to take out the static defences of the bases you are attacking. The basic idea of this strat is to destroy all but one of the enemy’s expansions. This strat works best when the enemy has around 2 to 3 expansions is when this strats works the best. Position your troops just outside the sight range of the enemy bases, one army per expansion. Once in position tell them all to attack their different targets. The enemy will either save their base(s) or attack you. The reason I call this Russian roulette is because it’s a gamble with very high stakes. If the enemy counters you instead of saving their base(s), or completely kills all your troops and attacks you before you can rebuild, you’re in trouble. On the bright side, pull this off and it’s nearly a sure victory for you. To win with this you will need a good income yourself (2 mines at least) and enough buildings to be able to pump out reinforcements.
Best Races – All
Counters – Level 6 Arch Mage or multiple TP scrolls.

DEFENSIVE MANEUVERS

Regrouping
The most basic of all defensive maneuvers is to retreat units so that all your units are together again and back in formation. Once you have regrouped you can turn around and continue to fight. Remember to turn off formation move until you turn around so that your faster ranged troops aren’t waiting for your slower melee units to get in front of them.
Best Races – All
Counters – Chase down and kill any units straggling behind.

Defensive Flanking
If you see an enemy massing just outside your base move your troops away so that the enemy will engage your towers first. Then, once the enemy attacks, flank them, killing of the siege (if you still have towers left), casters, and ranged units as fast as possible.
Best Race – All
Counters – If the enemy doesn’t warp in almost as soon as you attack expect them to flank you (they will either do it purposely or accidentally). To protect against this place your melee units behind your army and your ranged units next to the enemy buildings. The problem with this is that there may be towers to avoid, they may be buying another TP scroll, or they may just not have noticed you attacking them in which case they will warp in soon. There is also the problem of your ranged units attacking the enemy structures, which ups the required micro.

Defensive Ambush
An advanced regroup, the defensive ambush is to run away from the enemy and lie in wait. When the enemy troops enter the ambush slaughter them.
Best Races – Night Elf are by far the best at this as shadow meld needs next to no micro (just hit I). The other races can also accomplish this if the terrain allows for it. As you are running send half your army in one direction and the other half in another direction. When the enemy chases one half of your army send your other half in from behind. Human invisibility is not a good option, as it takes too long to cast on your entire retreating army (that and you’ll have one sorceress still visible).
Counters – Chase them down before they can prepare for an ambush. Against the Night Elf you may have to warp out unless you see them meld or have invisibility detection.

Extra Info

Don’t try to perform these moves if you don’t have good micro, don’t even think about it.

If the enemy likes to use the one maneuver over and over expect it, and counter it with another unit maneuver.

Only use Russian Roulette if you KNOW 100% that you can beat the static defence with 0 to 2 deaths max. RR also works great if you have just beaten the enemy’s troops.

Use invisibility moves when ever possible to give you an edge.

Buy a gem of true seeing so that the enemy can’t use invisibility to give them the edge.

And lastly, practice these maneuvers. They are NOT a use-first-time-and-win-fairly-easy type of move (unlike orcs and orc casters in particular).