12Hatch opener (You are trying to get a fast economy, but are vulnerable to a bunker rush).
9 - Overlord
12 - Hatchery at Nat
11* - Pool
*It can be 11 or 12. 11 is more safe, but it cuts a drone.
In the event you get bunker rushed, use your zerglings to attack the SCV making the bunker. If you have no zerglings
then pull 6 drones off the mineral line to delay the terran as much as possible. With good enough micro, your drones can repel the terran force. Even if all those 6 drones die, you are then tied with him economically, because, think about it. He has to disrupt his Build Order and pull 7 SCVs off his line, 2 of which may die.
A standard followup from a 12hatch, 11pool is this:
13 - Hatchery
@100% Spawning Pool - 2-6 Zerglings
16 - Overlord
16 - Extractor
@100 Gas - Lair
NOTE - Make Sunken Colonies as necessary
22-24 - Overlord
@100 Gas - Zergling Speed
@60% Lair - Hydralisk Den
@90% Lair - Expansion Extractor
@100% Lair - Research Lurker/Build Evolution Chamber (+1 carapace when done).
(optional) @100% Lair - Spire
@50% of Lurker research - build 6-9 Hydralisks.
@100% of Lurker research - morph Lurkers.
Spend the rest on Speedlings.
That build order will deal with M&M, since A. you have a better economy than the terran, you can then push out with your lurkers and take an expansion and B. You have lurkers, which can only be killed by tanks. But guess what? You have speedlings, so the tanks are dead.
To deal with Terran Mech (You can recognize terran mech if they send a vulture to your mineral line to harass) then the Build Order is 3 Hatch Muta. Do lots of harass, make 3 sunkens at your natural and ONLY 3 sunkens. Remember, Terran has tanks, so if he sees you build 3 or more sunkens, they can just expand
. Once you do a lot of muta harass (as much as you can) then transition into Hydraling. Get speed upgrade to deal with tanks, and +! carapace to save yourself from the dreaded goliaths. Try to expand and take the nearest and easiest expansion near you. It doesnt matter if it does not have gas, since you went 3 Hatch Muta you should have a lot of gas left over.
Good Luck.
None.