I taught lessons my senior year of High School at a local music shop. They charged $15 for a half hour lesson. Teachers got $10.
Advice:
1. When you do talk to parents, ask them to be encouraging, and to gently remind their kids to practice. This way, they'll progress more regularly, keeping the student happy and the parent willing to keep paying for lessons.
2. If parents want them to learn theory/sight-reading/blahblahblah, and the kid is too old to be bothered with the silly Mel Bay guitar methods, give A modern method for guitar by William Leavitt on Berkelee Press a shot. Its challenging but rewarding.
3. Outline an attendance/missed lesson policy in advance. Make sure its understood and taken seriously. People ditching you wastes your time and is generally uncool.
4. I found that asking students for a song they'd like to work on a week in advance was best. This way you could give it a listen, and devote more lesson time to teaching it than tabbing it.
Hope thats some help.