LinkedIn is "the" site for professional networking. Everyone, in my opinion, should have a (complete) LinkedIn profile, should connect with everyone they know, should join LinkedIn Groups, and should use LinkedIn for job searching when they are in the market for a new job.

1. Don't Waste Your Time on LinkedIn
By Mahboob ali khan
Use it the right way!
If you're not going to do it right, there is no point wasting your time (and everyone
else's) on LinkedIn. LinkedIn is "the" site for professional networking. Everyone,
in my opinion, should have a (complete) LinkedIn profile, should connect with
everyone they know, should join LinkedIn Groups, and should use LinkedIn for
job searching when they are in the market for a new job.
That said, LinkedIn is not going to work for you if you don't identify yourself. I've
received several invitations to connect in the last week from people who didn't
identify themselves. Setting up a LinkedIn profile with "Private Profile" or
"Human Resources Manager" instead of your name and asking me to connect with
you isn't going to work.
I have no clue who they are and I wasn't going to try and figure it out. Most other
people, including prospective employers, wouldn't be interested in connecting
either. LinkedIn is for "real" people to connect which each other - that's what
makes it so successful and such a terrific networking tool.
If confidentiality is a concern, and I'd guess it would be if you're trying to stay
anonymous, simply be careful. Connect with only people you know well. Be
strategic if you're job searching while employed and don't announce it to your
connections. There are ways you can job search confidentially without
jeopardizing your current position.
Here's how to get started on LinkedIn - quickly and easily - so you can use
LinkedIn effectively for job searching and career networking. Once you've set up
your profile, here's how to make it stand out, along with examples of great
LinkedIn profiles.