When to build Drones

I’ve recently changed to playing Zerg. To get a better feeling for all the races I’m taking them one at a time, and well I suck at playing Zerg. Sure I can win with a basic roach rush but anything apart from that it gets quite messy have no idea when I’m supposed to push, when to expand when to do mostly anything, but yet the hardest part of all of them is when to produce drones, its basically the same as sc1 either produce units to defend / attack or produce workers to improve your macro and productions capabilities latter on in the game. But in sc2 you won’t have high ground advantage to save you, so it becomes even more important to know exactly what your enemy is doing at all times, because you don’t want to produce roaches for defense if the enemy is going for a more eco oriented build unless you build enough so you can actually do an attack and you don’t want to be making drones if a push is pending.

I find this balance between eco / units to be extremely difficult in sc2 and I more often then none end up building to few because im preparing for an attack that never comes until a bid latter. when I’m out eco’ed or I eco to hard and a M&M army completely punishes me for it.

Well in short I need improve my Intel-gathering, and adjust my play according to what I see or what I expect, but the error margin seems a lot smaller then in sc at least at my level of play