MSNBC has a useful warning about social networking sites: focus on one or two, or you'll get overloaded.

"In researching this column," contributor Eve Tahmincioglu wrote, "I signed up for as many of the networks out there as I could and what did I get? A headache."

It certainly seems like everyone in the tech industry has an idea for a new social networking company these days. That's even more true on mobile. But all you end up with, aside from a plethora of logins and organizational challenges, is a bunch of walled-garden networks where it's difficult to connect to everyone.

"There are two purposes to social networks," said Jason Alba, author of "I'm On Facebook, Now What?" and "I'm on LinkedIn, Now What?" in the report. "One is for networking, and the other is to enhance your brand." Since neither one will happen for a while, you might as well take the time to figure out the best one for your needs.

"It's not going to help your career if you have a bunch of profiles, or pages on a bunch of sites, and no time to check all the connections and news happening everyday," Tahmincioglu wrote. "It's better to focus your efforts and building a solid network on one site."

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