If you know a musical instrument, giving private lessons to kids in middle school and high school is extremely lucrative. Especially if you live in a city with wealthy suburbs and competitive music programs. This is what my roommate from college does now. He was an allstate saxophonist. Sessions are usually 30-45 minutes for $70 dollars. He does about 15-20 a week in the north dallas suburbs. Some charge $100-120 per session if they are more experienced.