Because they like you.  They like you because you provide great value.  You provide great value because you care about your clients, about being efficient and reducing costs, helping them achieve their personal and business goals, and you give them freebies (i.e. free advice occasionally, CLE, and more).

The result: raving fans! Raving fans are

Are you marketing or are you developing business… DAH! Marketing IS supposed to develop business and so is client service and so is delivering excellent work product on time and under budget.

In my book there is no separation… all these activities are done in order to get more work. And everyone at every level