Are you connected with any other trades? See if you can provide your services to elevate or enhance the services of a fellow tradesman, just not someone doing the same work as you obviously.
For example, I refer work for two different painters and contractors. So if one of my clients needs their house painted I will refer one or both of the painters depending on who is busy. I usually then talk to the painter to give them a heads up and to see if they want me to pressure wash the house to prep it for painting. It saves them some work outside if is is hot, or if they are already doing other jobs and are trying to squeeze it in. I will usually then have the client have me come back to clean the windows after the painting to ensure that there are no paint specks or overspray, etc left on the windows. (Both of the painters I use are really good about this anyway so choose who you link up with wisely.)
The contractor that I work with has a deal with a window manufacturer and he does a lot of replacement jobs then has me come and do a CCU/install cleaning once the code inspector has been by. He charges the client $18 per window, I charge him $15 per window. Then I talk to the client to see if I can get them on a maintenance schedule of every 6 months.
Have you tried to link up with anyone at the local chamber of commerce? I was brought into a mingling event by one of my commercial clients and I met a few potential clients, one being an architect firm, the other is the commercial realtor that had me put in the bid for the 3 story commercial building and his $2 million personal mini-mansion ($1000 PW house + Windows, every 6 months). I am waiting to hear back on both of those jobs for July.