Wally has been in direct sales before. I can tell by his posts.

Let me try and put your mind at rest Paul.
Canvassing for window cleaning work has to be the easiest "SEll" of all.
Some years ago I needed to raise £2000 per 4 weeks of new work window cleaning. I started to knock doors between Christmas and New year. Of course I didn't knock on new years eve or new years day.
By the 18th of Jan I had the work. I only had one nasty person answer the door. No problem I just said good evening and walked away.
The worst thing that can happen is that the prospective customer says no. You will generally find that people are fine.
Dress smartly (Not in a suit) Have some printed info with you to show at the door and just say that you are expanding your window cleaning business and ask them if they want a reliable, professional service. If they already have a window cleaner thay are happy with just say thank you for your time and hand them a leaflet.
If the first question they ask is how much ask them if they already have a window cleaner and state that you do not undercut fellow window cleaners. (Basically walk away diplomatically)
If they do want a window cleaner they will treat you like a long lost family member. Remember to look all around the property with them and whilst doing this make a big thing of frames etc being cleaned then confidently give them your price. If you get 60 ish % of the houses you quote for your prices are right for the area.
Personally I wouldn't waste my shoeleather delivering leaflets then going back. Take them with you and put them through the "No answer" doors and make a note of the address. Then call back a few days later. I would also only canvass after 5.30 ish. Many people are out all day and you will get many more non answers during the day.
I would finish canvassing by 8 pm at this timer of year. Of course if you do have time to spare then deliver your leaflets during the day then follow them up.
You will hit hot spots where you get loads of new customers and also others where you don't seem to be getting anywhere. Just keep at it and remember that the next door you knock could be your next new customer.
Go get em mate. They are out there waiting for you to call.

All the best with it.
Andrew