By Cassie Holman
MoneyMix Contributor

If you're in tune with social media, you've likely heard of the infamous "Cisco Fatty" Twitter fiasco of 2009.

After being offered a job with Cisco, one Twitter user posted a tweet:

"Cisco just offered me a job! Now I have to weigh the utility of a fatty paycheck against the daily commute to San Jose and hating the work."

A Cisco representative swiftly responded.

"Who is the hiring manager. I'm sure they would love to know that you will hate the work. We here at Cisco are versed in the Web."

"Cisco Fatty" was busted.

social media has exploded

Facebook reports having more than 400 million active users, with 50%—that's 200 million users—logging on daily. Users post more than 25 billion pieces of content each month and spend more than 500 billion minutes on the site monthly.

 Get the latest on Facebook privacy settings.

 Build your personal brand online without risking your job.

 Learn how hiring managers view your online presence.

Here are more social media stats from eConsultancy.com:

• Twitter has 75 million user accounts.
• Toward the end of 2009, the average number of tweets per day surpassed 27.3 million.
• LinkedIn has more than 50 million members worldwide.
• More than 700,000 businesses have active Facebook Pages.
• More than 3.5 billion pieces of content are shared each week on Facebook.

There is no denying that social media use has exploded. The "big three" networks—Twitter, Facebook, and LinkedIn—as well as smaller, niche communities, are teeming with valuable professional contacts and networking opportunities. It makes sense to be online.

But to do so is to make your personal information publicly available. The latest research from Cross-Tab—released Jan. 27, 2010 on Microsoft's fourth annual Data Privacy Day—reveals that about 80% of U.S. recruiters and human resource professionals screen candidates' online reputations, and 70% have rejected them based on what they've found.

The flipside is also alarming: According to Cross-Tab, fewer than 15% of consumers believe that information online will affect whether or not they get a job offer.

Social media can be a powerful platform but, to reap the benefits, you must be smart about how you use it.

your handshake is not your first impression

Dan Schawbel, personal branding expert for Gen Y and author of "Me 2.0: Build a Powerful Brand to Achieve Career Success,"  has advice for students wondering how to use social networks to their advantage.

"The nature of first impressions has changed," says Schawbel. "It's not only about your résumé or cover letter, or the strength of your handshake. The first impression could be a Google search, or a retweeted link that an employer clicks through."

Schawbel continues, "The sooner students wise up and really think about what they are putting out there, the better off they'll be in the long term."

one student doing it right

Zack Zaban, 21, a journalism and mass communication major and business certificate candidate at the University of Wisconsin-Madison, has a strong social media presence. After graduating in May 2011, Zaban hopes to pursue a media-buying position with an advertising agency. Social media, he says, has a direct correlation to his field.

Search yourself online, and set up a Google alert for your full name and any nicknames or common misspellings.

Zaban uses Facebook, Twitter, LinkedIn, and Brazen Careerist, and maintains his own personal site with a blog.

Regarding his "social media brand," Zaban says he tries to portray his thoughts in a relaxed fashion.

"I try to use the following formula when presenting myself in the online sphere: a little professional, a little personal, and some light-hearted humor," says Zaban. Before posting to public profiles, Zaban says he does consider the potential effects of his message.

use privacy settings

You know that employers will check social network profiles, so decide where to make yourself available. 

"Some people say it's best to be completely transparent with social media; however, I disagree," says Zaban. "There are ideas that I want people to hear, such as a challenge I overcame or a portion of journalism ethics I agree with. Yet, there are portions of my life that simply don't need to be public."

Facebook is a favorite among college students. If you choose not to use Facebook for professional purposes, change your settings by visiting the privacy settings page. You also can use Facebook Friends Lists to separate your contacts, and allow each list access to different parts of your profile.

so, how should you use social networks?

You know you shouldn't post embarrassing photos or updates, but do you know what you should be doing?

Check out these social networks:

Student Branding Blog: Dan Schawbel's online network for students; the author of this article is a contributor.

Brazen Careerist: Social network and career management tool for Gen Y professionals.

Ning: Create or join niche networks.

Twitter: Microblogging platform.

Facebook: General social networking.

LinkedIn: Professional and career networking.

Schawbel recommends Twitter, Facebook, and LinkedIn as the top three networks for students to join.

Twitter is ideal for making first impressions, he says. You can reach professionals in your field by following them, retweeting a link they post, or sending them a direct message. After initial contact, it's easier to take those connections to other online platforms.

"Consider how you want to position yourself and how to play to your strengths," says Schawbel. "Create your profiles to reflect your own personal brand." He also suggests having the same full name and picture on all social networks.

Then, "Share successes, post interesting articles, showcase achievements, or share something from an organization you're involved with," he says. "[These are] things that strengthen your presence."

Unfortunately, you can't control what others post, but you can make an effort to monitor your image. Search yourself online, and set up a Google alert for your full name and any nicknames or common misspellings. Also, ask friends not to post questionable content involving your name. That includes flagging your name in pictures you wouldn't want employers to see.

"It's important for young professionals to practice simple common sense when using social media. If you post something to a public profile that you wouldn't feel comfortable saying in a professional setting, then you probably shouldn't be saying it," says Zaban. "Some people, in my opinion, do not realize that their 'online identity' can certainly have an impact on their 'offline identity.'"