What player had the biggest influence on you as you learned the game?
While watching replays what was one thing you saw that had a big impact on your game?
What did you realize about the game that allowed you to see more in the replays?
In any competitive game watching replays is an essential part of learning, whether you are just starting or have played since vanilla. Indeed those of us who went away for a few months then came back quickly realized that we were way behind, not because we forgot our builds, but because the game has changed, optimized by the leading players, whose gameplay was quickly adopted by the replay watching community.
Having grown up on Seton's Clutch my favorite player to watch had been Character(before he tried to quit, which really had a bad effect on his gameplay). Watching him play the rock spot with cybran was a great learning experience, especially seeing how he would maximize build capacity on his power production, using early reclaim for mass. This realization opened up the space of possible build orders dramatically. Early reclaim means you can move mass extractors further into your build, which in turn opens you up to many possibilities, getting earlier air, getting earlier t2 mass extractors, getting earlier T2 navy, etc.
Watching character made watching other players on other maps much more productive. The first thing to look for now, is what engineer from the initial factory goes to what piece of reclaim on the map.