When I started, I really pounded the streets. You have to try multiple methods because each one may yield one or two students and that can then add up. I went to music stores (selling cds) and asked to put my biz cards out. Most were happy to do it. There are also bulletin boards in places like
Sam Ash, Guitar Center, Borders and Barnes & Noble where you could post your card. I put my flyers and cards on every bulletin board I could find, especially at Universities. I also hired a kid to go out into family filled neighborhoods and put out flyers. All that stuff is good to get started, but the best method of all is personal referrals. Once people get to know you as a teacher, you can really gain students through their friends and family. It's a huge part of our business now. So much so, that I give away merchandise to current students who refer us and have a friend or family member start up with us.
Best of luck with it!
paul