The beginning is probably same for any race - as I start building 9th worker, i send one to build supply depot/pylon or spawn an overlord, then I can continue building workers fluently without hitting the limit (or hitting it for a split second). I also scout with somwhere around 10 - 13 worker - you shall see if the opponent is planning a rush by the time your worker gets there.
Then with zerg, I usually go straight for roaches, spawning only few zerglings if I have some extra larvae that just lies there. The only time I think it's worth spawning lots of zerglings from the start is when you see oponent teching fast and skipping the weakest units (almost) completly. But I still prefer to rush with roaches and maybe just a bunch of zerglings - that can be an instant win against:1. terrans that didn't go marauders, 2. protoss that didn't go stalkers 3. zergs that massed zerglings or had smaller force than you
. If 'toss masses stalkers you need to switch to zerglings quickly.
The continuation of this strategy againt protoss (which I found on b.net forum and never had the chance to fully test because ai is mostly dead at this point) is to continue pushing with zerglings and roaches while teching to lair and building a spire. By that point, protoss may start building immortals which are the best counter against the roaches, and should kill them quite easily with a bunch of zealots defending them. That's where you switch to mutalisks - easily killing immortals, zealots and probably winning the game for you.
I also forgot to mention - I always send my overlord towards the enemy base in the beggining - and if the enemy turns out to be zerg or toss (you'll know by it's worker scouting on you , or by your worker if it the opponent isn't scouting in the beggining), you can scout freely with that overlord for quite som time - in protoss base until he builts cybernetics, in zerg until tier 2 (of course , watch out for cannons and spore crawlers).
Too tired to write more. I hope this would be at least a little helpfull. And sorry for all the grammar mistakes.
EDIT: now I read the topic again and see that this maybe isn't exactly what you wanted ..nevermind, spent too much time writing this to delete it, there are still bits of info you may find helpfull
Then with zerg, I usually go straight for roaches, spawning only few zerglings if I have some extra larvae that just lies there. The only time I think it's worth spawning lots of zerglings from the start is when you see oponent teching fast and skipping the weakest units (almost) completly. But I still prefer to rush with roaches and maybe just a bunch of zerglings - that can be an instant win against:1. terrans that didn't go marauders, 2. protoss that didn't go stalkers 3. zergs that massed zerglings or had smaller force than you
. If 'toss masses stalkers you need to switch to zerglings quickly.The continuation of this strategy againt protoss (which I found on b.net forum and never had the chance to fully test because ai is mostly dead at this point) is to continue pushing with zerglings and roaches while teching to lair and building a spire. By that point, protoss may start building immortals which are the best counter against the roaches, and should kill them quite easily with a bunch of zealots defending them. That's where you switch to mutalisks - easily killing immortals, zealots and probably winning the game for you.
I also forgot to mention - I always send my overlord towards the enemy base in the beggining - and if the enemy turns out to be zerg or toss (you'll know by it's worker scouting on you , or by your worker if it the opponent isn't scouting in the beggining), you can scout freely with that overlord for quite som time - in protoss base until he builts cybernetics, in zerg until tier 2 (of course , watch out for cannons and spore crawlers).
Too tired to write more.
I hope this would be at least a little helpfull. And sorry for all the grammar mistakes.EDIT: now I read the topic again and see that this maybe isn't exactly what you wanted ..nevermind, spent too much time writing this to delete it, there are still bits of info you may find helpfull