There are a lot of very technical and quite good answers already, so I'll add a different piece of advice: play with others as much as possible. I realize you a

There are a lot of very technical and quite good answers already, so I'll add a different piece of advice: play with others as much as possible. I realize you are specifically looking for theory advice, but even so - music theory is only contextually useful when applied. If you strictly want to compose or analyze, surely the grammar and syntax of the language will be imperative for you to master. However if you're looking to be a better player, absolutely nothing else compares to having conversations with others. Music is the purest language, a distinctly human form of expression, and as whole is much more than the current meta-theory-craft. Alas, I digress.