If I were you I'd talk with your music teacher(s) and ask what it was like to begin teaching in your home state. They will have a good idea about the process for a credential/certification if public school is the route you'd like to go. They will also be familiar with the universities near you, and be better equipped to speak about the strength of those programs.
Regardless of the type of educator you'd like to become, you must start now with diligent practice of your instrument. If your school offers a music theory or AP Music theory class, that would be a good thing to take so you can get a head start on your fundamental knowledge of college music study.