Spot on LB.
I also love the suggestion of being involved with a client's business. When I hire someone to do a service for me, I want to know that you know that you care about my results as much as I do. I'm not a number. I'm a person, and my success means your success. If you understand this, you're going to give me the best that you can. This means I'm going to keep coming back to you, and I'm going to refer my friends to you.
If you just treat me like I'm a one-off project, of course I'm going to leave the first chance I get. You may do a good job, but you see me as a paycheck, and not as someone who can keep you in business. I can go shopping at Walmart for that experience.