I aim for a target then offer large discounts until i reach that number.
Eg If i wanted 100 customers i would offer the follwoing discount
1) First 50 customers get 50% the first 3 cleans.
2) Next 25 customers get 20% off the first 3 cleans
3) Next 25 customers get 10% off the first 3 cleans
I would also offer affiliate schemes like reccommend a friend and get a free clean. This way you will have them pouring in. Set your prices at whatever you want but make the customer think they are getting a good offer.
ALWAYS include Buy Now or For A LIMITED PERIOD. make sure the customers have the incentive to buy now instead of thinking on it.
These are little offers i use when canvassing but just remember once you have past the first 3 cleans your charging full price

Good luck