If your self taught and you plan on taking music courses in college, you should probably prepare yourself for ear training. Matter of fact some colleges will hold you back (or not except you) if you have poor scores in this area. So if you have neglected this area, I'd suggest getting into it before applying. There are tons of programs you can download, or books you can look into.

Here are areas to focus on.
* Recognize and name intervals from unison to major sevenths when played.
* Recognize and name all four basic triads (major, minor, augmented, and diminished), along with the dominant chords when played.
* Recognize the four scales used in western music (major, natural minor, harmonic minor, and melodic minor), plus the whole tone scale when played ascending and descending.

If you get at least an elementary level on those, you should do just fine. It should give you a headstart, cause ear training on a college level is probably the hardest course.