People want to do business with those they like and trust. Building trust takes time, of course. There are also ways to build trust that are simply good business practices, no matter what kind of business you have.
Be impeccable with your word. Never miss a deadline, and never charge for “extras” that really aren’t extra.
Produce the best work possible to help the client meet their goals.
Be upfront with challenges to client projects. I’m the professional, so I often know more about the project than they do.
Reward great clients with tokens of appreciation: gifts, experiences, bonus services and, most importantly, referring them to others. They’ll do the same.