Anyway, something that I've learned recently is that I can't necessarily hold my natural against strong enough early pushes. The two things that really put it together for me were 1) that I need to be ahead on econ for the most part, and that means making MAXIMUM drones; and 2) that by doing so (e.g. the traditional early zerg expand somewhere between 16 and 20), I'm pretty weak against very strong one-base pushes.
I actually lost a couple games due to this recently, but finally I figured out exactly what I was doing wrong. If I *see* when my opponent's pushing out, I have time to react. Throw down a couple spines at my natural to buy time, try and hold if I think I can, but if not pull back into my main. More often than not my opponent will kill my natural hatch before he pushes up into the main, which gives me a bunch of time to macro up some units. From there, as long as I have what I need (seems like usually banes against early Terran, roaches against early Toss), I can usually kill off the push, reexpand, and maybe apply some pressure of my own.
So, in other words, I need to be more active with scouting so I know when he's gonna show up on my doorstep to kill me (and, for me, this has meant sticking Zerglings outside his natural, on watchtowers, etc), and also I need to know when I can't save something, and not throw away too much trying to do something that ends up being futile.
I'm sure this is probably common knowledge to a lot of people, but it's something that I only really saw clearly a couple days ago. I was talking to a Masters-rank Zerg, and he mentioned that sometimes it's necessary to pull back and let them beat on my hatchery, along with really emphasizing the whole "know when your opponent is going to do something" thing. Once I started applying that, I started seeing serious benefits in my ladder games.
Edit: FTP fail. Fixed link now.
This is a link to the replay of a game I played this morning against a heavy one-base Terran. It wasn't perfect by any means, but I think that it really showcases what I learned.
The one thing that I haven't been doing is staying a couple Overlords ahead of where my supply is. I've ended up getting supply-blocked midgame when my opponent kills an Overlord. Maybe I need to be more forward-thinking when it comes to Overlord production, just in case something like that does happen.
Either way, I really think I'm starting to see beyond the build orders and look at more how exactly the game's played. It's an interesting transition for me, from mechanics to kind of a primitive game-sense.
On a completely unrelated note, SC2's matchmaking system is putting me up against gold-league players now, and things are becoming much more difficult. I've been in silver for something like three weeks (and have only played 8 or 9 games). Isn't this a bit soon?