<p>Very good. Another really helpful thing to do is learn scales, they're really easy on the guitar because of the movable shapes. Also, you know those chords you learn as a beginning guitar player like E, D, A, C, and G? Learn what notes are in those chords, then learn as many more chords as you can and learn what notes make up THOSE chords as well.</p>
<p>You don't really need to be able to sight read on an instrument to be good in AP Theory btw. Work on becoming fluent in both treble and bass clef, including knowing the key signatures. Memorize what those chords I just told you to learn sound like, and more importantly look up songs that use simple progressions with them (like C F G) and internalize how those chords sound in that order.
Cuz honestly music theory (at the AP course level) comes down to knowing scales, harmony, tools that composers use in their writing (like inverting a melody or using tones that aren't part of the underlying chords), and of course being able to hear all of that.</p>