Haven't done canvassing for a while, bit of a numbers game really, you can hit an area or day where everyone says no even before you've started to speak.
I don't consider myself anything special on the knocker, I can get quite ill before going out, but my conversion rate out of people interested in window cleaning was around 4 out of every 6 ( two thirds )
I found Sundays 10 am to 1 the best, more people in, always relaxed, and overall friendly.
Friday evening the worst and the last few days of the month before payday
Darran