This is something I'd be interested in doing.
You would need some before and after pictures, large ones. Also some kind of sign to get peoples attention. You could have equipment on show.
Alternativley you could have a sign with a fascia / conservatory pic on saying your company name and what you do.
Competition to enter for a free fascia or conservatory roof clean. People fill in a form with their details.... Name, address, tel, email, a little survey on their property cleaning (windows, fascias, conservatory, gutter cleaning)
Maybe try to get it in the local rag ?