Use your 4 miners go mine, start with minerals closest to you.
Keep making drones every 50 minerals you have, use all to mine.
When you get to 9th drone, use it for Spawning Pool
Now you get a second 9th one (duh) use it for a sunken
Use next drone for sunken too.
Use Next drone for Extractor
You should have a healthy amout of minerals now (around 150)
Make an OverLord, and a Drone, use the drone for mining
When overlord is done, keep making drones, lots of them, use 3 for Gas
try to get most of your minerals mined (leaving 3-4 unmined is ok)
When you get 100 gas, Evolve your hatchery.
While hatch is evolving, Make around 2 more hatcheries.
If you have extra money, use it for more miners
Finish mining all geysers
Make around 3-6 Overlords, you'll be needing them
Make 2 drones
Use them to make a Spire, and a Queens Nest
When Queens nest finishes, evolve your hatchery again
Make More Hatcheries
Right when the Spire finishes, you should have around 4-8 hatcheries
Evolve the Spire to a Greater Spire
Use every hatchery to make Mutalisks, until you can't
Go attack someones mining!
Keep it going!
When Greater Spire finishes, the person you attacked will suspect more
Evolve 12 Mutalisks to Guardians
You should see side defense coming from person you attacked
Destroy their defense, and send in more mutalisks
Leave 2 hatcherys open (having a total of 3 larvae)
When your guardians are mutalisks are attacking, spawn 12 zerglings
Attack with your zerglings attacking the the front of their base
Make 2 zerglings attack at a time so they suspect a mass attack
Mass up your mining if you didn't yet!
Make sure to defend your base!
Keep making Mutalisks
Keep sending in your Mutalisk
Evolve around 5 more guardians
Evolve 1 Devourer and make it patrol the outside of the persons base
Stop making mutalisks, and let the attack continue
Don't waste anytime, make a hydra den!
Research Lurker
Evolve around 6 hydras to lurkers
MAKE MORE OVERLORDS
Make lots of hydras and go in through the front
Make zerglings, and attack through the front at the same time
use the guardians to attack STRUCTURES ONLY
Use the left over Mutalisk to defend the guardians
Send in the extra 5 guardians you created
Send a few drones to scout for any expansions
If the person you attacked was an expert, he should have many troops
Send in more hydras and zerglings if he does
If your attack force got killed, then go in with lurkers.
Burrow 4 lurkers IN the base where there are lots of units/buildings
Burrow 2 lurkers IN the base where there are less buildings
Use all your hatcherys to make mutalisks
Send 3/4's of them to the 2 lurker spot
send 1/4 of them to the 4 lurker spot and have them tear things up
IF those 1/4 of lurkers get killed, send in your 3/4's force
Send the 2 lurkers in with the mutalisks
Spawn only 1 egg of zerglings
Send them in, if they survive, mass up on the zerglings
Unburrow whats left of your lurkers when the zerglings get there
Bring the lurkers to the choke out of the base and burrow them
Watch the workers run, and die!
Make 12 Scourge and make them scout with the Devourer if its alive
If Devourer is dead, forget about it, you won't need him no more
If the Expansion is weak, send in ALL your workers to attack
It might sound stupid, but just do it
While the expansions workers are attack your workers, keep them coming
Send in ALL your mutalisks to attack the base
If you find a big expansion, send the attacking force to kill it
Leave 12 zerglings to kill the remains of the old base
Have fun while he begs for mercy
Allyhim, or kill him, your choice!

CreepColony's Opinion: Watch out for a zerg's worst enemy; psi storm.