Ty, There are so many ways. I am sure you have business cards and flyers.
Let me list a few.
My favorite suggestion is to get active in the community.
Pick a cause. (like Heart Disease, Breast Cancer, Lou Gehrig Disease) and support it.
Get your local newspaper or T V station to do a piece on you and the cause.
FREE advertising and you WILL attract customers.
Another way is to be a vender at trade show or info show.
Good luck, LUCKIEST
I would reach out to the many cleaning companies out there and see if you can offer your services as a third party vendor to them. Cleaning franchises are very popular and pop up all over the place. Most do not focus on windows but general office maintenence.