£1 per unit. (if it's plain glass)
A unit being each frame of standard size, bay windows count as 2 units, small (lets say down stairs toilet window) 0.5 units.
Each climb of a ladder counts as 1 unit.....do not over reach, so if 2 climbs are needed no matter what the size then it counts as 2 units.
3rd floor windows (if he is mad enough to want to do those) start at 2 units per climb.
Time: to do a 3 bed trad style with experience about 15 -20 minutes.
Marketing: Cheap home pc printed A5 leaflet does well for beginners, leave the tri fold glossy stuff for when more experienced, these are for the posher end of the market.
Poaching: If you get a customer who changes from one window cleaner to another it's either because the last one was unreliable, rubbish at it or too expensive for them. Look for new estates that have gone up these are best.
leaflet then follow up the next evening with a door knock and "Did you get one of these leaflets we put out yesterday.......blah blah blah."
Is that a better response?