There is no major secret formula, but what I am going to tell you is relevant to anyone who owns a business right now. There is a significant portion of businesses that get most of their customers from this one things. Some businesses are making millions by doing this!
The key, in fact, is to offer something for free! You own a law practice? Offer a free book! Carpet cleaning business? Offer a free cleaning with two paid rooms! Retail store? Free makeup tutorial! Tattoo and piercing place? First piercing free!
If people like your work they will keep coming back. I don't know about you, but I find it much easier to trust someone once I've gotten to understand them a bit. Free helps ease that passage between "Are they trying to pull something?" and "I love that company!".
Every business has something that can be given away. What do you have that you can start offering?
Martin J Glennon