It's all about spending your resources as soon as your getting them really. The better your macro gets, the more units you get out in a period of time (aside from timing attacks you should scout).

Really the difference between bad players and good players aside from not building counter units is their macro.

yeah, that's exactly how i felt playing against better players. they just had more "stuff", although i didn't see any major mistakes in my play. well, i guess i just have to play more :v