A nice sign on your car when park in a upscale high traffic area
Word of mouth but you need more then that
Yellow pages is good but not good enough, pricy but good, they need your phone # when they look up in "DETAILING" in yellow pages
If you build it they will come
A cat & mouse, reach out and withdraw, like "This service is not for you", you can screw it up if not done right.
People are not stupid
Look professional, dress professional in good work uniforms, do you home work on what you have to offer, avoid words like da, I don't know. You have to be in control so does the customer. Have good communication skills, like confronting, listening.
Run down cars are not worth doing "blue book value"? Reach out to higher end cars, that might take time in your experience in knowledge in Detailing. Knowing things like back of your hand in detailing is a most, that's why more cars you detail the better. Ops I'm blabbing sorry LOL