Originally posted by: thomsbrain
assuming you're interested in rock, blues, or pop music:
not to discount part of what mandala said, but i've found music teachers at schools to be tragically square, soul-less, and not up-to-date on any guitar music made in the last 30 years. ask them about rock and they'll say "yeah, i listened to santana but then i got bored with rock, and now i only listen to folk music," or something equally uncool. i'm sure there are exceptions, but i have yet to meet one.
i would suggest finding a local independant music store, and ask them if they have recommendations for guitar teachers. many will have several brochures that you can take and read to see how they are qualified or what they specialize in (one guy might do metal, another might do blues, etc). call them and ask for references if you're worried, or just try a few lessons with one and see how they go. if you feel you are learning, and you're enjoying it and getting along with the person, then the person is right for you.

i picked my teacher at random from a music store and he was great. i only stopped taking lessons from him when i moved away. he taught me to be a musician first, a player second.