zerg
• build about 10-15 hatcheries.
• get 400 zerglings (kill your drones to do so), put them all in overlords and drop them in the enemy base. (if enemy is toss, then spread out lings)
- special thanks to andrew to
• at the beginning of the game, don't send all your drones to 1 mineral.
• hydralisks are a very strong massing force.
• when attacking a zerg team, always bring a detector.
• ultralisks run as fast as zerglings. (they're just bigger so they look slow)
• at the beginning, send zergling/overlord to scout for the enemy.
• if you rush, get zerglings right away without building anything else.
• devourers can make enemy air unit attacks slower by attacking it. (the spores make enemy's slower weaker)
• when attack zerg, fly anti-air units into the base to destroy overlords. After that, attack them with cloaked units. =D

protoss
• if you rush don't build a forge/cannon, just get gateway (at least 2) and get zealots as fast as you can (1 pylon too)
• dragoons are a very strong massing force. (better than hydralisks)
• massing archons isnt always a good idea. (they're big and could get stuck in small places.)
• when attacking, send dark temlars last in the attack force.
• when being attacked by carriers, attack the carrier and not the interceptors.
• always build more than 1 pylon around buildings. (un-neccesary against comps)
• if attacking a bunch of cannons, always attack the pylon instead of the cannons unless theres only 1 cannon.
• use dark archon to mind control scvs/drones. (so you can have all 3 races)
• put reavers in shuttles, fly them to the enemy base (command center/nexus/hatchery/lair/hive) and drop reavers there. ("reaver drop")
• when building cannons at the beginning, dont build more than 8 at the entrance.
• use distruption web on cannons, turrets, bunkers, sunkens, sieged tanks, and spores.

terran
• if attacking with infantry units, have at least 3 medics with the attack force.
• at the beginning of the game, make a wall at your entrance with supply depots, build bunkers behind the supply depots, and put tanks behind bunkers. ("bunker")
• if nuking, put "cloaked" ghosts on the cliffs and then nuke. [ before | during | after ]
- special thanks to trong tran
• put sieged tanks on the cliffs of enemy bases. (dont forget to have goliaths for anti-air) ("siege drop")
• always have at least 1 comsat station.
• spread tanks out at your entrance. (If enemy has melee attack or is too close to your tank, then tanks dont attack.)
• valkyries don't fire if there's lag.
• goliaths were made for anti-air, weren't made for ground offense/defense.
• if an air unit flies into your base, use your medic to blind it by use "optical flare".
• lift factory off base, put factory on cliff of enemy base, build siege tanks.

all
• never hack! (be warned, bnet removes starcraft accounts and cdkeys permanently if you do so)
- special thanks to andrew to
• always have anti-air spreaded out in your base.
• never build neatly, wastes too much time.
• at beginning of the game, dont send all your peons to one mineral.
• if being attacked by melee units (non-ranged units), while using missle units (ranged units), attack the melee unit, then run back, attack again, and keep doing this. (doing this wont let the enemy attack you while you're killing it!)
• when selecting a unit that can attack, press "a" and left click to where your destination is. (this makes it so you attack any enemies in the way)
• send units to the entrance of the enemy base so that the enemy'll send all their units to the entrance to defend, when they do that, send air units to attack the side of the enemy base.
• never have more than 3 peons at 1 vespene geyser.
• build turrets/cannons/spores (if cannons then have more than 1 pylon around it) around the sides of your base. (or cliffs)
• keep units that can attack air units around your base for protection.
• when you attack, either don't bring all your units or build more units while you're attacking.
• if you're being attacked and there's no chance left for you base, run your peons to a different base (your ally is a good idea) and start building right away. (never send all your peons in the same direction or the enemy will know where you're running to)
• never squeeze all your bases together, because if there's a nuke then you're screwed.
• never have more than 1,000 minerals/gas. you should be building/upgrading enough that it never passes the 1,000 point.
• if using protoss, and the enemy is terran (only comp), then get some dark templars. (do this fast) then run dark templars into the computer base without attack anything, goto the comsat station and destroy it. (for some reason they wont scan you) after that, destroy the rest of the base.
• when rushing, send all your units that can attack except for your peons. don't build any buildings to upgrade. don't build a defense. just attack all your units asap! (rush with allies)
• never build what you dont need!