Patches are old school. Go for it m8 you wont regret it.
Get as much advice and information as you can off the forums and you wont go far wrong.
Leaflet drop and door knock around your local area, if already got a window cleaner leave alone, respect other cleaners as you you dont do to them as you wouldnt like done to yourself.
You can tell straight away if they havnt a window cleaner just by looking at there windows and its these customers who havnt a window cleaner you should be targeting.
Theres plenty of advice on this forum to help you prosper. Good Luck.