1. Make an impression with your connections.
2. Share your knowledge and be a thought leader.
3. Learn things.
4. Builds community relations.
5. Your profile footprint expands.
But you must remain active! Activity is key. One of my connections complained that he has twice as many instances of "LinkedIn" mentioned on his profile yet has a lower ranking than I have. It has to be activity that garners more views and a higher ranking than others.
So get out there and start networking and reading and sharing and expanding!