So you’ve decided that your company can no longer sit out the 24-hour virtual cocktail party that is today’s marketplace. But before you brave the new world of Twitter, Facebook, MySpace, LinkedIn, Ning, and others, take some words of advice from industry leaders.

1. Think about your customer first, says Sam Ford, director of customer insights at Peppercom Strategic Communications in New York. “What are your customers talking about? Where can you find a community that’s already engaging in that conversation? How can you resonate with your clients?”

2. Choose the social-media platform that fits with your brand, your corporate culture, and your customer. Alyssa Ilov, vice president of marketing for architecture, design, and engineering firm Astorino, in Pittsburgh, decided that blogging was the way for her company to enter the realm. “We wanted to position ourselves as industry experts, and a blog felt like it was easier to get our arms around, allow everyone to really play a role, and get them engaged.”

3. Completely fill in online forms, urges Gail Sideman of Publiside Personal Publicity, in Milwaukee, Wisconsin. “Write a profile. Highlight your basic role, add some personal anecdotes, such as hobbies or the kinds of music you enjoy. It humanizes the professional you.”

4. Listen before you tweet, post, link, or share, advises Denise McVey, president of S3, an agency specializing in advertising, marketing, and public relations in Boonton, New Jersey. “Offer something of value, something that reflects who you are and why you are there. Frequent interesting, informative, and valuable updates are good.”

5. Be honest. “Never use social media to pull the wool over people’s eyes,” warns Ford. “Users will be more likely to trust you if you’re transparent,” he says. And that could prove handy when negative feedback comes up. “Your clients are more likely to defend you and stand by you,” if you’ve been up front.

6. Make it meaningful and interesting. “People want to know the nuggets of your life,” says Richard Laermer, author of Punk Marketing. Share what’s on your mind—in a succinct way. “The most effective posts are those that get to the point, stop, and leave people to draw their own conclusions,” he adds.

7. Err on the side of caution. “One major pitfall is that social media provide a quick, unfiltered voice from companies to the people,” says Dave Anolik, chief creative officer of Portland-based Quango Design and Marketing. “That has the potential to place executives in legally actionable situations.” Also be aware that anything released to the public can affect your stock price and market share.

8. Set realistic goals for your campaign and clear measures of success. Consider what strategies you need to develop and how you are going to achieve them. Don’t be afraid to seek out help from the professionals, but keep your voice.

9. Re-tweet, repost, and link to other people’s stuff. The more you integrate your efforts with the larger community, the more people you can reach, experts say. Another benefit? By showing your customers that you respect and value the opinions of others, you create more credibility.

10. Be involved. “There are more than 122 million blogs, but only about 7 million of them get updated,” says Laermer, an avid blogger and Twitter user. “The reason I update often is because I know that if I don’t, people will move on.” And that means money left on the table.