Thoughtless: According to Dixson, don't post profile pictures that are "too sexy, cartoonish or that might alienate your audience." A look through your friend list can usually reveal the ones she's talking about. The stylized glamour shot, the quick snapshot of slicked up hair or low-cut dresses taken right before heading to a party, or worse, costume-like pics: wet suits and surfboards, bike gear, Halloween outfits —the list goes on.

2. Filling Out Your Biography

Thoughtful: The biographical section of social networks vary. On Facebook, the service provides fields for a variety of interests, both professional and personal. Don't be afraid to post some nuggets that convey who you are, within reason. On Facebook, you can decide with great granularity what information people can view by altering your privacy settings. For instance, you can set it so every visitor to your profile sees that you enjoy golfing, reading and civil war history, but maybe only a certain group of people see your religion, political affiliations and relationships. For Facebook's "About me" section, building on the Twitter doctrine, Dixson says to be short and concise. Don't worry about being clever.

Thoughtless: While there aren't many numbers to back this assertion (because Facebook is a private company, and data can be hard to come by), most social networking and identity experts believe a great many Facebook users never so much as glance at their privacy settings pages. The same probably holds true for other social networks. Remember that social networks plan to monetize their service by ensuring that you share as much information as possible. As such, you should believe that they'll share as much information about you as they can, and make it available to the widest audience.

The default settings for Facebook, for example, make all your profile information available for everyone on the service to see. "Assume from the get go that anything you put in there is viewable on the public internet," Dixson says. "Go in with that line of thinking. Then go in and say, if you don't want to make certain information available to certain people, go turn them off with the privacy settings."

With the information you do share, avoid being vain. Social networks do enable, if not encourage, a bit of narcissism. But don't assume people want to read a novel about your life. Also, be protective of your family. It's fine to list yourself as "married" in the info section, for instance, but don't necessarily feel that you have to put down a link to your significant other. If you have young children, for their protection and privacy, Dixson recommends you don't include their names anywhere in the bio or in pictures of them that you decide to share.