That's about it in a nutshell, I prefer this 'soft' sell approach, if it's a no I offer a leaflet and move on.
I can vary the lines a little out of boredom ie.. "We clean your neighbours in the street, Would you like a regular window cleaning service"
This the standard sort of line.
"Good evening, were local window cleaners, would you be interested in a cleaning service"
Dress smart but casual, don't crowd the doorway and be confident, not only delivering your line, but explaining ( if the potential customer is interested) your quality, your frequencies etc. keep it short and simple.
Darran