I enjoy canvassing too. Make sure you're clean shaven and look smart and tidy. I have never worn a suit as I think that's a bit too much but some jeans with a shirt and jumper works for me.
Keep it brief. I say, "Sorry to disturb you, I wondered if you'd be interested in a LOCAL window cleaning service?"
Most are very polite but there's always the odd exception. Some can be sensitive to this. I couldn't give a monkey's quite frankly - just find it sad people are like that. If no-one's home leave a leaflet and record the house number discreetly. I memorize 4-5 numbers at a time then jot them down. If you get someone that's interested then ask to take their details there and then. As you must have just started use a template something along the lines of:
Name,
Address,
Phone,
Price,
Frequency,
Access to rear?,
Any additional notes.
Try and charge first time clean extra charge, extra 50% or so. Hardly anyone objects if you explain why. You'll be glad you've done this when you start your work as they're pretty time consuming. Plus some will cancel after the first clean when their windows are spotless and you've slogged for an hour for a tenner. Annoying but true!
All this works for me. Admitted I hit a good area but I managed to drum up 100 customers in 2 months when I started last year... Email me if you want any advice.