Every websight I have seen that tells you how to select and buy a guitar are directed toward adults with money. I am not even in high school, so none of these help me! I have picked up quite a few tricks of the trade from my grandpa. I will teach you how to find a good deal on a used guitar, and what to look for in any guitar that you might want to buy. I have 5 guitars (on 1-14-12) and I got most of them very cheaply. The acoustic below is a Takamine gs 330s. It sells new for $324, but I got it for $125, plus I got it with a case.
Step 1: Acoustic or Electric?
Acoustic guitars generally cost more than electric guitars, but it evens out after you buy an amp and a cord (requisite for an electric guitar.) Acoustic guitars are better for people who want to just pull their guitar out and play, or for people who would like to take their guitar places. Electric guitars have amazing effects, and you can distort the sound as much as you want, to accomodate for any style of music. Both of the guitars below are the ones that I have bought myself. The electric is a fender squier affinity series telecaster. The acoustic is once again my Takamine.