As I am only just purchasing my first WFP system, (a trolley one from Broxburn cleaning products £1351) I cannot really offer much info as yet on WFP, but I certainly can on starting a business.
By far and away the best method is to get out there and sell yourself and your service by knocking on doors, combine that with a well written flyer, and like Justin, add some photo's too and you will be well away.
Adverts in local papers may well work, but can often lead to work spotted around all over the place, though if and when you do advertise, when you do pick up work from it, follow it up by knocking on all the doors you can find nearbye and post your flyers into the letterboxes of the houses that have no one in.
Where I live, and where the majority of the domestic work I had (all commercial now) it was very rural.
Knocking on some of their doors could often lead to them looking at you like you are a burglar casing the joint, but these areas rarely have window cleaners due to their relative remoteness, but darn worth it to pick them up, and you can charge good money for your service too.
Where possible try and cover at least your travelling expenses, not always easy if the house is just a straight forward semi though!
Best of luck!
Ian (ISM CLEANING SERVICES)
