Call the school and ask for the sponsor of the National Honor Society. When you get in touch with that person, have a list of things you might want the tutor to work on (for example...Latin, advanced math, chess, geography, strategy games, etc.) and ask for a list of names of students who would want to tutor in any of those areas plus be a mentor. What they worked on together would depend on the high school student that you select in the end.

I would have all interested students send you an email resume and letter and I would send them what the commitment would be (how many hours a week, how many times...like once a week for an hour or twice a week for an hour).