What theory is needed? I know all the basic stuff, (rhythm, time, key signatures, all that), plagal, half, and deceptive cadences, and some basic chord progressions (I-IV-ii-vi-V7-I, etc), as well as the basic forms for different kinds of music (sonata, rondo, etc). What else do I need to know, and what are some good websites for learning it?
If anyone here lives in Oregon, I'm at an OMTA (Oregon Music Teachers Association) level 6, if that helps.
Also, I know all 12 major and 36 minor scales, as well as dorian and phrygian modes.