You be the judge. Reflect on your abilities and make a value judgement of how much they are worth per hour. If the student is a beginner and you feel you have the ability to assist him, I would look at the $5 to $10 range per hour. Look back at your former lessons and try to give back to them as much as possible. When you find that you have extended your ability range, pass him on to a more experienced teacher. This could be could for you. You always learn from teaching others and walk away feeling that you have accomplished something. This might even give you an opportunity to experience teaching and the opportunities in that field. My wife has found it to be a very rewarding career and I enjoy teaching trumpet to my students.