LinkedIn is fast becoming an important part of the modern "Job Search 2.0," a powerful way to build your network and your professional brand, according to Neal Schaffer, the author of Windmill Networking: Maximizing LinkedIn.

"Recruiters and hiring managers now see LinkedIn profiles as an alternate resume, and sometimes go looking for employees before they receive your query or even before there's a job opening," Schaffer says.

But many professionals don't know how to take advantage of its potential and therefore miss out on opportunities. "LinkedIn has a lot of potential to improve your sales and your visibility," says Arden Clise, etiquette columnist for the Puget Sound Business Journal. "But many sign up and then forget about it, or they don't use it in the ways they could."

Here are the dos and dont's of using LinkedIn:

Do Complete Your Profile

Experts suggest writing your profile in a way that demonstrates value. And you should include a photo, according to Clise. "People from the past contact me, but if I can't see them or if they haven't filled in their jobs or education, it's possible I won't know who they are."

Do Make Your Profile Unique

Liz Ryan, a former Fortune 500 human resources executive and the leader of AskLizRyan.com, advises using the LinkedIn profile to create a strong personal brand. "We already see way too many 'results-oriented professional with a bottom-line orientation,' so use your profile to tell us more about what makes you tick and what sorts of business situations you're looking for."

Do Write a Headline

Ryan adds that the headline field under the name is an important but often overlooked branding tool. "Put a human voice in it," she advises. "You don't need to put your current title in that headline field. Tell us who you are as a working person. 'B2B trade show marketer interested in the intersection of social media, content and trade shows' is a lot more interesting than 'Trade show manager, XYZ Plastics.'"

Do Ask for Recommendations

Well-written recommendations can be strong selling points. But use this feature judiciously, advises Schaffer. "Recommendations make sense only when they come from someone you've worked for, he says. "Friends who say you're great don't have much weight on LinkedIn."

Do Take Advantage of Groups and Advanced Features

Being active in LinkedIn groups is a great way to find connections and build your brand. Schaffer sees LinkedIn groups as a "virtual industry conference."

Do Give

"Don't start asking out of the blue for favors," Clise says. "Approach any network, including the one on LinkedIn, with the intent to give and serve others, so when you need a favor, others will be glad to reciprocate."

"There are a million ways to contribute, but a great one is the LinkedIn answers feature," Ryan adds. "Browse through the questions others have asked and lend your expertise there. It's a good way to get your ideas out there and make some contacts at the same time."

Don't Brand Yourself a Job Seeker

It may seem counterintuitive, but recruiters and hiring managers often prefer "passive" job seekers to people who are actively looking, according to Schaffer. "It's the issue of 'We want someone who doesn't need a job,'" he says. "You can talk about your experience, your expertise and your value on LinkedIn, but if you brand yourself as actively looking for a job, it may not have the effect you intend."

Don't Spam

Using the InMail function to send bulk messages only clutters up your contacts' inboxes and wastes their time. If you want to communicate, use the Q&A function, interact in groups or ask people to sign up to the auto-responder. If you join LinkedIn groups, don't flood members with emails like "See what I have to say on my blog."

Don't Ask for a Connection with Someone You Haven't Met

LinkedIn is about professional connections. The emphasis should be on quality, not quantity.

Don't Annoy Users with Extraneous Updates

Professional-sounding updates to your profile can be a good way to keep yourself in others' minds. Unlike with other social networks, however, updating on LinkedIn more than once a day is overkill. And irrelevant updates can hurt your brand more than help it. "I gave a presentation at a local small business seminar last week," is an appropriate LinkedIn update. But "I just had a yummy fruit smoothie" is the kind of thing that's better for other social networks.