Zerg tactics
Basic Zerg Hydra Rush:
This is about as easy as it can get. You don't even have to rush them right in the begining of the game to win with this tactic. I usually get a decent defence, like 5-7 sunken colonies at the begining of the game before I do anything else. Then I get the gas and minerals I need to get a hydra den. With that, if I've already been attacked at this point I would add a few more sunkens to my 5-7. I get a lot of drones to get all the mining and gas done, usually around 30-50 drones. I'd find some place to put 3-4 more hatcheries and try to mutate them all at the same time, then get about 2 evolution chambers and I'm set. Once all of this is done, I'm ready to start building up my attack force. I go to each hatchery and start mutating the larva into hydras. If I have enough money I upgrade the weapons and then the armor for the hydras. I keep adding to my defence and mutating hydras intill I'm ready to attack. I wait intill I have about 4-6 groups of fully upgraded hydras though. Basicly, that's about it.

Will be getting screen shots in here soon so you'll know what I'm talking about.