If you want more followers.... get your audience involved.
If you want more customers... get your audience involved.
If you want more results......... get your audience involved.
I could go on, but I won't. You get the point. Contests, interesting content, discussion... GET YOUR AUDIENCE INVOLVED.
How to Succeed in Business Without Really Trying has done a good job of this. The Broadway show held a contest for its fans. See the winner in the video below: