We get quite a bit of new work from recommendations from the local double glazers.
Titancleaners - as already stated, if you just go out and distribute your 15000 flyers throughout your 20 mile radius (40 mile catchment area), you will end up with very few jobs from it, you are spreading yourself too far and wide. We have all done it in the past and all that happens is you end up very despondant at the lack of work you have got for all your effort.
Do some research, look at whether peoples windows look clean or not, if they don't knock on their door and their neighboours, and present yourself and your flyer to them, tell them you are cleaning in this area and would they like their windows cleaned. If they are not in, then you put the flyer through the door and call back later.
We have a small ad in the local paper every week (£10.50pw) if we get a call from it and it's a new area we tell the customer that it's not an area we cover, but we will canvas the area and if there is enough business we will start cleaning there.
We then go out and canvas that area hard over the next couple of weeks to see what the response is. Quite often the person rings back and says she has found some more customers for us. Had a call on Thursday, woman presented me with 8 house addresses that all wanted a window cleaner in the same street, they haven't seen their previous cleaner since October.
Good luck