For a social network, LinkedIn is remarkably hostile to young professionals. Unlike Facebook, where it is apparently acceptable to “friend” someone on the (sole) basis that they share  your first and last name, LinkedIn has rules.

Some rules are made to be broken, like “Don’t connect with someone you’ve never met face-to-face.” Others are not only good manners; they’re zealously enforced by the network itself. A good example are the many roadblocks which are designed to prevent you from sending invitations to perfect strangers.

Consider this excerpt from Dave Taylor’s blog post about LinkedIn ettiquette:

LinkedIn users vary in their views on how well you must know someone before connecting to him or her, but it’s inappropriate to send connection invitations to people who have never met you, heard of you, or had any inkling of your existence (unless they have indicated a desire to be approached by strangers).  Think about it:  if you found a person’s phone number on a scrap of paper, you wouldn’t feel that you had permission to phone him.  Your possession of an email address doesn’t give you license to contact an unacquainted LinkedIn user and suggest a connection–and it’s this kind of overzealous outreach that gets users in trouble with LinkedIn, as well.

Taylor’s advice is good, but it also reveals the extent to which LinkedIn favors people who are already highly-connected. LinkedIn has so many protections because the network wants to encourage seasoned, high-profile professionals to use it. I’ve never sat in on a LinkedIn strategy meeting, but I imagine their rationale is that highly-connected professionals = potential employers. Where there are employers, job-hungry grads and mid-level professionals will follow. Of course, you can’t attract and retain highly-connected professionals without offering them some degree of protection from annoying solicitations.

Seasoned professionals love Linked In because it’s a great way to “digitize” their  existing contacts on a platform that constantly updates itself (no more bulky Rolodex!) But for those of us still in our first decade of work, Linked In is about building a network. But how do we do that when LinkedIn has set up so many roadblocks to connection? Here are some ideas:

Connect with sales people, vendors, and others who want something from you.

Entry-level and mid-level professionals are often dealing with sales people, since bosses usually rely upon their underlings to do purchasing research. Use this as a free opportunity to build your Rolodex. Connect with anyone who you are exploring as a potential vendor. Not only will the numbers boost help you look more connected to potential employers down the road, but you can also use these connections to practice giving more than you get from your network.

What can you give sales people? Leads. If you experience great customer service from a salesperson, plug their product or introduce them to another of your connections who might be interested in what they have to offer. It doesn’t matter whether your employer decides to buy. Connect with the sales person anyway.

Join a group. And then say something.

Groups are the loophole in the LinkedIn firewall. LinkedIn will allow you to connect with an apparent stranger if you share group membership with them. That doesn’t mean that you should join a group and immediately start connecting with all its members. It does mean that you should join relevant groups and participate in the conversations going on there. If you find yourself having a side conversation with a particular member, move the conversation off the forum and into your inbox by offering to connect with them. Then, keep the contact “hot” by maintaining occasional conversation or shooting them a link to an article which may interest them.

Be active elsewhere on the internet.

My rule of thumb is that if you’ve had three or more meaningful web interactions with a person, it’s okay to connect with them on LinkedIn. Some great places to go for conversation are:

• blogs
• forums
• twitter
• Brazen Careerist (and its new service, “Network Roulette”

Encourage current friends and colleagues to join LinkedIn.

In this economy, everyone needs to network. Most importantly, everyone needs to be able to easily reach the contacts they’ve already established. LinkedIn allows you to do that. If a contact switches employers, LinkedIn will update that information without you having to chase them down for a new business card. Convince others to join, and welcome them to the community by inviting them to connect and writing a recommendation for their profile.

Introduce your connections to each other.

If you know two people that could benefit from getting to know one another, offer to introduce them. Not only are you keeping your contacts fresh through interaction, but they may return the favor.

Have a LinkedIn uber-session after returning from a conference or business trip.

I recently attended a conference in which all the presenters provided their email address for follow-up questions. There was also a directory of the conference attendees included in the participant folder. When I got home, I immediately connected with the presenters and attached a “thank you” for their presentation (with specific points I appreciated or wanted clarification on). Then, I went through the directory and recalled five people who I had briefly conversed with between sessions, and connected with them too. Of the modest fifteen people with whom I had connected, I received a detailed, friendly response from all of them.

What are your ideas to help an entry-level or mid-level professional get the most out of LinkedIn? What’s worked for you, and what hasn’t?