I play the Zerg, mainly because I always just turtle with Terran(Siege Tank, Bunker, Missile Turret, repeat) and I have much love for the purple little suckers.
I'll set my loving drones to work at the minerals while using the starting minerals to create new drones, which also harvest minerals. Continue until you can make an overlord and use a drone to morph into a spawning pool simultaneously. Then, while keeping an eye on my base(Creating vespene geysers and increasing the drone population), I use two spawned 'lings' to arrive at the lookout points early(Allowing me to spot early enemy movement).
Using a drone for an evolution chamber and creating another overlord, I morph the hatchery into a hive while using excess larvae to create more 'lings' to make a suicide party. When the Lair is evolved, I spawn a queen, using a few drones as defensive spires. When the Queenie arrives, I evolve burrow and increase my drone population and send out another Overlord(Setting these critters on patrol routes along the perimeter of my base). At this point, the Queen will have been busy spraying my lair with her goo. Using the new larvae, I create a small wealth of Zerglings(Evolving Zerg carapace) to join the other few units I have. I spend a drone on a hydralisk den(Burrowing my zerglings at the lookout points when it evolves) and send a small percentage of zerglings at the enemy base to observe their progress in order to decide whether or not to rush them.
If so (My queen has sprayed the lair a bit back), I spawn a good deal of hydralisks and a few zerglings to wipe them out.
My extended strategy evolves with the enemy actions.
