Different people use Facebook for different things. But by and large there are some common rules to get involved without drowning into some selfish monologue.
The obvious way to grow your network of contacts is through friends of friends. Just like being introduced at a party you broaden your horizon by the intermediary of someone who knows both parties and acts as a go-between.
There the analogy stops. If you don't post straight away on the wall or your new friend but merely let them read your stuff we don't have a conversation going - simply someone thrusting a brochure into someone else's lap...
One of the telltale signs of a marketer in guise of a cyber friend is the number of posts versus the number of comments. If there are lots of the former and none of the latter this is a lone self-promoting account. (Some of them are just automated RSS feeds publishing blog articles from other sources.)
Another thing to watch for is the number of friends your new contact has. If it is above a few hundred chances are it is impossible to keep up on a personal basis with so many people. This could be another self marketer in disguise or simply a celebrity in arts or entertainment.
Another approach is to look for fan pages or interest groups that share your values. The page itself might not be that crash hot but the people who "like" it might be worth talking to. You will have to step out of your shell and introduce yourself.
Some people use Facebook to keep up with relatives overseas and share photos. Others use Facebook to play silly games and you get invite to find a lost goat in Farmville...
Facebook has more than 500 million active users, which is about one person for every fourteen in the world. You would be considered a dork if you didn't want to be on it!
It's a great way to spy on your teenage daughter or find out what your ex is up to. It's so easy to open a fake account. The police and the FBI are on Facebook to stamp out teenage stalkers trying to groom an unsuspecting soul into meeting them at a public location. That's definitively not what you would call a quality connection. School pupils are not innocent either. They have used Facebook to defame teachers who have no avenue of redress. In French Canada Facebook is referred to as fessebook (fesse = buttocks) and the website shows the hind part of a cow. Some of us have seem the movie The SocialNetwork which gives some insight as to its sleazy start on campus.
So Facebook is here to stay whether you like it or not - you might as well make the best use of it.