As Shaun quite correctly states , start high and as you mean to go on . The first lesson taught to me by Mike Halliday and although perhaps not as high as shaun and Mike I do not consider myself on the low side.
the very first suite I cleaned was proberbly the worst I have had to clean , stains, spots watermarks everywere. 5hrs later yes 5 hrs later i was done, and although not all the areas were immaculate the customer was delighted with the results. It gave me confidence ,and with time comes experience which helps build that confidence. so stick to a decent price and dont worry about been turned down
I believe if you show confidence you will succed, if you look uncertain or apprehensive you will lose the custy.
Geoff