If you have to canvass then you must not be doing your job properly or you look unprofessional. I never canvass or beg for customers! I simply start my van and the phone rings, people run to me and beg me to take them on as a customer, they get rid of their old window cleaners and employ me, even though I'm more expensive! They e_mail me and tweet me to please take them on, they offer me their sacrificial daughters as play things if only I'll clean their windows!
I'm not just any window cleaner, I'm a JD Window Cleaning Services Window Cleaner......