I used to tutor. I'd place an ad in the local high school paper and post flyers around their campus, with their permission of course. Be sure to advertise which courses you can tutor. Don't just say you can tutor Math; say you can tutor Algebra, Gemoetry, Pre-Calc, etc.
I always preferred to help with homework and studying for tests, and I had them bring their textbook and some recent assignments. Parents who want someone to help their child "brush up on skills" were a red flag to me because I'm also a teacher, and I came to recognize those students as needing help far beyond what I could do in an hour or two a week. The students were often way behind, totally lazy, or had undiagnosed learning disabilities. Someone else might not mind that kind of tutoring, but I found it very frustrating, especially after a full day of teaching.
Edited to add: I saw that you asked about pay in another thread. I think this probably varies from location to location. I charged $40/hour, which was super cheap for a credentialed teacher in southern CA. The going rate was $60-$75 for an experienced, credentialed teacher. Around here, I'd suggest you start out around $35-$40/hour.
