The invites to join LinkedIn, Facebook, MySpace, Ryze.com and other social networking sites are flooding your inbox from friends, colleagues, former co-workers, college classmates and even your boss. Do you accept them all or weed some out? And how can you build upon these relationships to advance your career?

Like much of our virtual existence, the rules for online networking follow those of the real world: Following up is key, flattery works and don’t put something in writing if it could hurt your prospects.