I would never do first cleans at half price,no wonder this buisness is the way it is with people charging ridiculas prices,have a bit of respect for yourself and if not charge double charge half your initial price again,theres alot of people around my area charging half if not less what I charge and I cannot see how they make a living especially if they are FULLY INSURED and PAY TAX,
If you quote really really cheap people will think your a cowboy that is signing on and working at the same time,I like to think I quote fair,maybe a bit over sometimes and I always tell people you get what you pay for when they tell me the last guy only charged me half that.
Like I say have some self respect because you will never get anywhere doing jobs really cheap.
As for techniques I clean the frames every time,only takes a few seconds and makes a hugh difference,remember the frame too is part of the window.