I remember that the local library was the place for finding ads for teachers. Also, the further education colleges, large supermarkets and schools. Okay, they may not stick your ad up, but they'll be aware of the info.
Put ads in the libraries in all the towns close by. Think carefully about the ad. People can be put off by cheap looking or hastily scribbled ads. First impressions are important. Especially for parents who want a sax teacher for their 'little darling'!

Are you a well educated and responsible person with whom they will feel safe leaving young Natasha, or are you just an ex-busker desperate for money to fuel your heroin addiction?
Perhaps an eye catching motif/clipart thingy at the top, but then a neat and serious presentation of you and what you offer.
Good luck.... and don't forget my commission!
Steve