I've just done my first month window cleaning fulltime and know exactly how you are feeling.
It was just the same for me when i first started looking.
There are around 8 or 9 local w/c's in my town which i thought after a few evenings knocking on doors is it really worth it.
But if you want this to work keep going, it will come. I'm not making thousands but just enough to pay the bills etc. I haven't canvassed or put leaflets out since i started fulltime but have people phoning through recomendation.
Some of these people already have a w/c but aren't happy with them.
Never undercut on price just put in what you think is a reasonably price.
I have found out that i have quoted more than there present w/c and they still want me. I gave a price the otherday which was double what they were already paying but because they had seen a neighbours windows and frames after i had been they wanted to change to me.
I still have days where the phone doesn't ring or have a quote turned down, but i know more will come.
Keep at it matey don't give up. Handing my notice in at my old job and doing this was the best thing i could have done. It makes you feel good
Craig