Assuming you have taken care of the basics, I believe the best way to draw in more/repeat customers is
marketing & advertising.
The best form of advertising for me by far has been the 3' signicade signs that I create for myself, I put them right next to the street. I have about 40-50 of them, change them regularly. It attracts a LOT of attention, people quote them to me in the grocery store, school functions, etc. Always hard to be certain at a self serve, but I think it has made a big difference in revenue.
I also alter them into 12x18 versions and put them on the columns between the bays (these are mostly advertising), and 8x10 versions for plastic stand-up picture frames - these go on the counter at the bank, fund raisers, etc.
For example the last 10 days has been a "pollen" sign. Tomorrow will switch to mothers day. Then nothing for a week or so (maybe the pollen sign for a couple days), then memorial day signs. I'm currently installing the air shammee blow dryers, so probably the month of July will be an ad for "New blow dryers, try it free during July" - one version for the signicade, one for in the bays, and one to put an ad in the local paper.