[jrockway]

Reading.

Programming is 10% writing code, and 90% reading code. Reading your own code (debugging, refactoring, coming back to something you wrote on Friday on Monday), and reading other code ("why doesn't this library work?").

Once you learn to read, a number of things happen. You are no longer a slave to your libraries; you can open them up, see exactly what they're doing, and either change your mental model or change the code. You don't have to get stressed out about "coding guidelines" anymore, because you actually understand what the code means. Inane details like tabs versus spaces and cuddled elses or whatever don't matter anymore, because you have seen all the possible combinations. And, you pick up the style of your peers, because you aren't coding in a vacuum anymore.

I could go on and on, but if I boil it down to one action item, it's "when you have a problem with a library, read it". Everything else comes from there. (And before you know it, you'll be mentioned in the Changelog of everything you use! Good for getting your next job.)