Linkedin is a more exclusive social network than the other ones. So it's definitely harder to connect with other users. You have to start out by making contact with people you actually know. If you're new to the site and have just done this, then you'll probably be wondering how to grow your network further.

Basically, you've got to get on the radar of other Linkedin users and prove that you are a genuine person with expertise in your field. A couple of really good ways of doing this are using Linkedin Groups and Answers.

There are many groups on the site and they are quite active. While some of them have been a bit overrun by spammers most haven't. When participating in them it's really important to have a good photo of yourself in your profile. This appears as an avatar next to your contributions, comments and likes. If your face keeps popping up in these discussions, then it's inevitable that some people will have a look at your profile to learn more about you. Needless to say, the odds of this go way up if what you're adding is thoughtful, relevant and interesting. Keep doing this and some of those who have arrived at your profile this way will decide to send you an invitation.

As you browse the many posts and discussions in your groups, you'll identity certain people that you want to connect with. You can keep an eye on their activity in these discussions by "following" them. If you "like" their contributions from time to time and comment on them you will certainly get on their radar. (Of course you shouldn't be obsequious when doing this. That might just put them off.)

After a while you can then send them a connection invite. They'll know who you are, and the chances that they'll accept are far greater than if you did it without any prior contact.

Another good option is to use the Answers section, in which people seek the advice of countless professionals. It's definitely worth scouring this section for questions related to your interests. Offering thoughtful solutions to the queries listed is an excellent way of showing your expertise at the same time as lifting your profile. Remember that your answers will be seen by other answerers and browsers, as well as the original questioner. And if you write what he judges to be the best answer then that will be recorded in your profile, increasing your credibility.

You can also get great benefit simply by asking questions. After you get some responses you should say thanks to each of those who were kind enough to answer. That's another way of getting on their radar personally. (This is actually a surprisingly effective method. I've asked three questions so far, and thanked everyone. As a result I've had two invitations which I've accepted.)

UPDATE: Linkedin Answers has just been removed from the site! Still, the groups remain, thankfully.

It goes without saying that you should be polite when using social media. There are a whole lot of good reasons for this.

For example, if you make a habit of being rude and obnoxious on sites like Facebook and Twitter it could effect your personal life, or even your career. Everything you post on such sites is findable now.

But being well mannered is also good for business. You just get more followers, fans, likes and retweets, etc if you are polite and helpful. And if you're widely perceived as being approachable as well as knowledgeable, there's a much greater likelihood that you'll receive interview requests and guest posting offers.

Here's just one little example of how being polite has helped me: Recently I posted a question on Linkedin Answers. I got several responses. You can rate the answers as "good" and "best", which I did. So I assume those people were notified.

But there were others I hadn't acknowledged. I hadn't used this facility before and thought there might be some sort of automatic thank button, like on Quora. But there wasn't. So I sent e-mails to all those who'd answered my question, thanking them for their valuable input.

Pretty soon after that one of these people, who's very well established and has a big network, sent me a connection request, which I immedaitely accepted. One of the other users who answered -- again with a big network -- e-mailed me to say he was happy to offer his advice, and not to hesitate to contact him for any other questions. So, a conversation has started there.

Such developments are hardly remarkable, of course. But I wouldn't have made those connections had I not made a point of saying thanks. Clearly, being polite on social media can result in immediate benefits.