Big, open-ended question, but I have some ideas.
First, think mobile first. Mobility and social is where a lot of the opportunity is, especially if you can integrate location and context into your offering. Some of the best social apps, like Foursquare and Instagram, take advantage of location as a value add to their offering.
Second, integrate. If you have a mobile app, plug into twitter, linkedin, and Facebook to leverage existing social networks that users already have. Integrate with user’s contacts if you can to make the experience more personal. Offer easy “invite” functionality to expand the user’s circle in the offering you are providing.
Third, provide a very simple offering that users can understand immediately, and one that provides value to customers or solves a problem they didn’t know they had. If you can’t describe it in one sentence, you need to simplify it.
Finally, focus on providing the best experience possible. Hire a user experience professional to test your idea with customers, and optimize the design to the channel/users needs.