If you are starting in a new area, here are a few ideas for building your business.
Offer to string free, once, for some of the well known players in the area. They will learn that you string well and you can say to prospective customers," I have strung for _________".
Put a new overgrip on every racquet you string. You can get them for less than a dollar each, and it will really make you stand out from the other stringers.
Make sure all new prospects are told that your work is guaranteed to be satisfactory. That if they aren't
happy, you will either give their money back or redo the string job.
Put each freshly strung racquet in a poly bag. These are available for about 10-20 cents each. This and the overgrip will only cost you about a dollar, but will really set you apart from other stringers. When your customers pull their freshly strung racquet out of the poly bag, like the pros on TV, the other players will ask,"who strings for you?".
Keep a rag with a little polish on it around your stringing machine. Wipe down each racquet to give it a new racquet shine. Takes about 15 seconds.
Maybe something here will be helpful for you.