If you are single, in my opinion the best thing you can do is get off Facebook if you're on it. Unless your account is completely information-free, it removes a lot of the mystery and allows too many people to peer into your lives. Not to mention it wastes your own time.
I have nothing against connecting with old acquaintances, but that gets old quickly. Meanwhile, as a Facebook "user," you are not a customer. Rather, you are an asset for the company to use as leverage as it rakes in billions from advertising. What amazes me is how people on Facebook (and not just teenagers) think nothing of "liking" a corporation, thereby advertising it for free. Time was, being a corporate tool was frowned upon. So was volunteering private information. No more.
Of course, what you're getting out of it is "connections." If you really think this enhances your happiness, more power to you. I find it overrated. My wife and I have both been off Facebook about a year and we don't miss it. I do maintain a page for my website (using a generic account) but based on my blog stats, Facebook has a minimal impact on traffic. Yes, blogging can be construed as a "time waster" too but I love to write, and prefer to operate a largely one-way conduit of information that I think others might find entertaining or useful. (I.e. not inane status updates.)
As far as meeting women and getting laid, again I think its impact is minimal. You still need to go out and meet women in the field; online resources are just one tool in the toolbox.
Lastly, not to get political, but let's put to rest that Facebook and/or Twitter somehow fomented revolution in the Arab world. Protests and coups happen because of circumstances. Maybe social networking helped, but in Egypt those sites were shut down and people still found a way to communicate and organize. I find it laughable that Facebook is given so much credit for world events. Give me a break.
(No one here has claimed that - more a criticism of what I've read in the news.)