One way to get people to respond is to put up a sign with the offer of something to fill out a survey - a dog treat or maybe something you can buy in bulk and personalize? A keychain, fridge magnet maybe?

Or, if you are able, to put together some stuff for a gift bag and pull a one of the finished surveys as the winner? Do this once a month?

How's about some special offers?

Like a coupon page?
Or offer specials on slow days? 10% off on Tuesday afternoons?
Can you do a "fourth appointment free" kind of deal?
You might offer packages - 5 dates for the price of four?
Make up some flyers with an "new customers" offer on the prices?

You might want to see what other spas are charging and use that as a guide for your own pricing?

good luck!