I've been window cleaning since 1988 and the best bet is word of mouth, once you're established.
Flyers also work, but it's best not to say you're just starting up, better to say you're looking to expand in the local area.
As for pricing up, here on the South Coast, I charge around 70p per footing and £1 for leaded or more difficult work.
Once you know your speed you'll be able to look at a job and know how long it'll take, and how much you wish to earn per hour (I'm an average of around £20-£25p/h).
Just sold 2 rounds in 6 months as can't cope with the amount and have charged 3x monthly income, all residential work in quite sullubrious areas,(just in case you get the chance of buying work)
Kind regards
Ducktack