Your career: The perils of self-promotion

November 15, 2011, 10:00 AM UTC

Twitter, Quora, Facebook: It’s never been easier to build a personal brand. It’s never been easier to mess it up, either. Here’s how to toot your horn – without becoming yesterday’s news.

FORTUNE — Shama Kabani spends much of her time teaching entrepreneurs and CEOs to promote themselves on social media. She wrote a well-received book, The Zen of Social Media Marketing, owns a growing digital marketing company, and stars in a web-TV show offering advice on building your brand and more.

Friendly and outgoing, Kabani, 26, defines her own brand as open, vibrant, and innovative. Yet her actions sometimes run counter to the accessibility she works so hard to project. She removed the “send an e-mail” button on her Google+ account after a barrage of “You’re so hot” and “I love you” missives. Then, in December 2010, Kabani abruptly stopped following all 16,000 people she had subscribed to on Twitter in hopes of eliminating a barrage of spam and other comments. “It became unmanageable,” she says.

Some followers took her decision personally. A few blogged about her “slash and burn” move; others called her arrogant and selfish. Kabani admits the decision may have resulted in a few lost opportunities, such as potential clients or organizations seeking a speaker. But it also led to a careful deliberation on how to balance her various personas.

Sure, Kabani is an author, a smiling multimedia answer woman, and a CEO in “an industry of transparency.” But was she, in fact, overexposing her own brand? “Someone once gave me advice,” she says. “When you start, you say yes to everything. As you grow, you need to learn to say no.”

With Google+, LinkedIn, Twitter, and Quora just a click away, there are more ways to promote yourself than ever — and just as many ways to screw it up. Worshipers at the temple of “just spell my name right” may have forgotten that overbranding can take someone’s reputation from Ferrari to clunker faster than anyone dreamed possible. Just ask Paris Hilton.

How to brand yourself like Ferrari

The temptation is particularly perilous for rising stars or newly promoted executives. They develop one success, and instead of growing it into a second and a third, they start selling themselves shamelessly. “The brand is your promise that represents real things that you deliver,” said Steve Cannon, vice president of marketing for Mercedes-Benz USA, a company that knows something about image creation.

Lyles Carr, a veteran recruiter at the McCormick Group in Arlington, Va., says he tends to discount a résumé that doesn’t list true accomplishments. “It goes back to the old commercial, ‘Where’s the beef?’ ” he says. “They’re trying to substitute style for substance.”

While it’s nice to be able to boast about the sheer numbers of friends you have or Twitter posts you’ve made, sometimes less is, in fact, more. James Alexander, CEO and founder of Vizibility, which helps professionals and job seekers control their online identities, recently turned off all the updates from a man on LinkedIn (LNKD) who posted every single hour. “He’s lost his privilege to communicate to me in that way,” he says. “You can spend all this time and effort — it does take time — only to turn around and end up alienating people.”

A better plan is to speak or tweet only when you really have something unique to say. Alexander says that when he’s looking to hire, he reads blogs and comments, hoping for signs of original thought. Often he is disappointed.

Some overbranders even leave reality behind by faking or exaggerating credentials and degrees — not too smart when Google (GOOG) is just a keystroke away. In the past decade, executives at Radio Shack (RSH), Smith & Wesson (SWHC), the U.S. Olympic Committee, Veritas Software, and more either resigned or were forced out after it was discovered that they had lied on or embellished their résumés.

While it’s easy to obsess over the number of your Twitter followers or Klout scores (a measure of social-media influence), many people have forgotten that their brands depend on more than pithy opinions on the latest news. Dan Schawbel, managing partner of Millennial Branding and author of Me 2.0, a personal-branding book, says the best strategy is to “be the go-to person for something, even if that something is as simple as Microsoft Excel data sheets.” He also favors offering really great advice and free insights. As you help more people, you build word-of-mouth referrals and job security, he says. Your brand becomes ingrained in people’s minds as useful.

Another classic trap is alienating your boss with your overzealous self-promotion. As Schawbel was building his reputation as a twenty-something personal-branding czar, he made sure he did it outside work hours and kept his boss in the loop. “Anytime I had a speech,” he says, “I would explain to my manager exactly what was going on beforehand.”

40 Under 40: The Twitterati

For Mercedes’ Cannon, the key to creating an elite brand is to “actively manage” your reputation. At the German car company, that means the Masters and the U.S. Open — but not other, more accessible, events. And while Cannon so far has skipped Twitter because he doesn’t see it advancing his personal brand, he is helping Mercedes wade in “cautiously” into social media. “Go for quality, not quantity,” Cannon says. “It really comes down to curation.”

So how should you split your time between the actual work you do and making sure others know all about it? Cannon thinks an 80/20 split is a good ratio, with 80% of your effort going toward the job and the bonds you build with co-workers and your boss. The remaining 20% goes into sharing your work and ideas and being visible through speeches, articles, or blog posts.

Of that outside self-promotion, Kabani suggests a 70/30 split: Most of it should be informative, entertaining, or educational, whereas 30% can be straight brand building. Here, it’s good to create a conversation: Instead of saying, “Let us create your next website,” post the seven questions one needs to ask before doing so — and then be sure to provide the answers. “It’s all about value,” Kabani says. “Social media is simply an amplifier. Doing the right things is crucial as well.”

At Kabani’s Marketing Zen Group, the 25 staffers strive to answer every e-mail that comes in — unlike other companies, which see it as a waste of their time. Today Kabani follows 955 people on Twitter, but she has 23,123 followers. Some are eager for her to write a second book; Kabani says she will wait until she actually has something important to say. “I needed to take my own advice,” she says, “and do something that worked for me.” Kabani wants a lifelong brand rather than 15 minutes of fame, and that takes discipline — which is, as we all know, a lot tougher than pressing the send button.

5 ways to keep your brand from going sour

1. Honor honesty: “If you … inflate your résumé in any way, be prepared for it to leave lasting damaging effects on your career,” says Hannah Samuel, an expert on reputation and trust. It’s way too easy to check things these days. A little exaggeration can lead to serious consequences.

2. No boosterism: When you leave a message or comment on a blog post, make sure you’re focused on “adding to the conversation,” says Dan Schawbel, author of Me 2.0. When you sign it, don’t list multiple websites or your slogan and a pile of digital identities. “It turns people away,” he says.

3. Stay in the moment: If you’re at a corporate event and all you do is edit your YouTube video or tweet, you’re not projecting a positive image, says Mercedes-Benz USA ’s Steve Cannon. Instead, he says, “drink it in.” You might get a real live opportunity instead of an online one.

4. Nix negativity: Don’t criticize ideas and people very much. Skip the snark. You don’t want to be labeled a negative person, says coach Rita Ashley. An alternative: Be an expert. Find three or so online communities in your field or interest area and create bonds, share ideas or information, or write reviews.

5. Be consistent: If your blog is seldom updated or your image swings from the 1% to the 99%, you’re hurting yourself. Make sure you’re clear on your core beliefs and target audience. Then be “systematic, patient, and intentional” about your brand for staying power, says Lida Citroen, author of Reputation 360.

This article is from the November 21, 2011 issue of Fortune.