[throwaway8879]

Another thing, I really do recommend learning music theory on the piano/keys as well as your primary instrument. Doesn't have to be a fancy keyboard, any cheap midi thing just to visualise the way the way chords and scales are structured. I've found that learning other instruments become a lot easier once you know a little bit of theory and how they're laid out on a keyboard.

[beat]

When I was learning theory, my teacher taught all his students, regardless of their instrument, on piano. It's the most neutral, in terms of scales and chords.

Guitar, on the other hand, usually has multiple valid fingerings (on different strings) for the same chord inversion. Part of the process of learning new chord voicings on the guitar is learning the same chord everywhere it can be played.

[garrettdc]

This is really good advice. With all the different places you can play the same note on guitar, it makes it a little more difficult to visualize. The one note to one key ratio can help to make things like chord structures and inversions make a lot more sense.

[skybrian]

Or maybe a melodica? They're cheap and fun to play. (I started out on piano.)

I think each instrument's UI has something to teach. The stradella bass on an accordion with its circle-of-fifths layout is pretty interesting.