I would concentrate on the window cleaning for now as setting up any other income stream will become a money drain until it is well established.
As for canvassing set your sights on middle class housing. Don't rely on leaflets alone. Knock on each and every door and introduce yourself, say you are the local window cleaner and ask them if they would be interested in having their windows cleaned if they say yes ask them if you can have a look at heir property and give them a price( do no cave in on the price otherwise you will be doing it forever) If they say no give them a flyer and say "if you change your mind in the future give me a call". Keep a note of not at homes and call back at another time. The best times for canvasing are early evenings, Saturday afternoon and Sundays however week days are good for elderly people. Make every time you are not working a canvasing day and you will soon be turning away work..... guaranteed.
I personally would insist they have their windows cleaned every month or two months otherwise you attract people who muck you around.
And just one more thing... To keep and build a customer base the most important things are 1, do a really good job 2, be punctual 3, be friendly and pleasant 4, dress respectably.
If you follow these things I guarantee you cant fail.