I don't really have the builds down by heart as I'm still studying them and I tend to just learn the basics (15hatch/14pool you build food to 15 make a hatch then make a pool kinda deal) and then just improvise from there but I can tell you what it is I tend to build for when it comes to the match ups
I'm a gold league player at the moment, started in mid December 2012 and recently made it to gold a couple days ago so bare with me as I'm not the best player:
ZvZ: I send a drone scout at 9/10 food to see if they pulling some sort of cheese. Once I see the opponent is not cheesing, I usually go for 14gas/13pool (I hear 15hatch/14pool is bad in this match up). I get speed for lings at first 100 gas and then, depending on how my opponent is reacting either pull off 2 drones from gas back to minerals or leave them. I make 2-3 sets of lings and send them over to harass. I make a queen also and inject asap. I keep from getting supply blocked and try to tech up to an expansion while harassing my enemy and denying their 2nd. Then I get a roach warren and build a lair. I drop an evo chamber for upgrades and prepare myself for transitioning into 2nd phase gameplay. By this point I'm usually set and go for Roach/Hydra/Infestor. That usually wins it for me. If they mass ling that comp ends it with festor's fungals (make sure to get the festor energy upgrade and to not build festors till that is at 30% complete) alone or you could drop a bane nest to scare them off. This match up,for me, tends to be come down to whoever can macro up to Roach/Hydra/festor w upgrades the fastest. O and try and sac an Overlord to scout. O and scout some more!
ZvP: Again scout at 9/10 food. I almost always go 15hatch/14pool against toss. I like stephanos 12 min roach max (love roaches!) while also teching up to hydras and infestors. If the roach max don't end it I tech up to hive and get broodlords out asap. If they 4-gate I drop a couple spines in the beginning and get ling speed asap. Queen it up too. Spines and lings should hold you off, even more so if you can get your queens in good position. I find Roach/Hydra can hold off a good portion of toss strats (air or ground) but don't just all in with these units unless you for sure can take them down. Scout also, otherwise they can hide a key building and blindside you. If they try and rush you with some zealots and stalkers mass speedlings and try and get surrounds while teching up to roaches. If they try to do quick void rays, get some queens out like 3, and try to scout it as early on as you can. Get a lair down and try to get to hydras. The queens should be able to hold you off for some time. Always try and get expansions as zerg need to be 1 base ahead of any other race to be to compete. If collosi come into play, try and engage them when there are few out of the field and try and keep your opponent from gaining too many in numbers. Scout scout and scout!
ZvT: Tends to be a hard match up for me. Again I scout at 9/10. I usually always go for 15hatch/14pool with these guys also. Unless I see some cheese like proxy rax or bunker rush. I also try and get speedlings out asap. I tend to go into these games with the mindset of me teching for lings/blings/mutas. Lings and banes in the beginning to handle the marines and marauders and mutas for any tanks they may have aswell as harassing. But I also adjust to what they are doing. If I see my lings are getting destroyed by their tanks/marines, I drop a roach warren and go for banes/roach play with some mutas in the mix. All while trying to deny them their expos and hit and running with the mutas (don't over commit in mutas either, try and keep like 7 or 8 out). If they are going for mech play, I like roaches and lings. Since mech is really slow, take advantage of it. Do hit and run attacks and never fully engage them. They can't split this type of army up so they send their whole deathball out at the same time. Try and stay away from this till and expand in opposite sides of the map. Once you have the economy, try and engage them off guard or hit them at their base when they are away.
As far as the late game goes - Broodlord infestor is considered the best. But Ultras/lings/blings is good too. Keep these army comps in the back of your mind and try and work around it incase you find yourself needing to get tougher units out to stay in the fray you won't be too far away. Some other things to keep in mind: You may need to remax your army a few times to deal with some of the races and their strats, don't feel worried its something zerg is really great at :) also try and spread creep as best as you can and remember to do your injects as well as getting a macro hatch to get more larvae out. Stay a base ahead and you'll be fine. Use the units you have available to the best of your power. O and did I mention to scout? Keep playing and keep practicing.
Just some stuff I keep in mind. Hope this helps. Goodluck! *meant 2012 not 2011
Edited by Luckylou on 1/29/2013 2:59 PM PST