How do you invite others to join you? You could be selling a new idea—or marketing yourself.

Let's look at four mistakes, using invites to LinkedIn as an example.

1) Never inviting anyone.

Hmm, this one's tempting. No one likes rejection; it forces you to relive high school.

I remember having a high school crush on Linda N. One night, I finally called for a date.

"Who exactly are you?" Linda N. asked.

"I sit on the opposite side of the room in English," I said. That didn't really explain who I was. It didn't even explain, really, where I was.

More about Linda N. in a moment.

Meanwhile, some good news: high school's over.

Last week, I invited 20 people to LinkedIn. Most accepted, a few ignored me. Nothing terrible happened.

2) Bad timing.

When I called Linda N. for a date, my timing was flawed, but only in the sense that it was already Saturday night.

"Yes," Linda N. said, "I'd love to go out—and I think my date's at the door right now."

Timing matters. Are your LinkedIn invitations too late, or too early?

"Don't invite within two hours of meeting," says Rod Hughes, Director of Communications, Oxford Communications.

"I typically wait till the next day," advises Rod. "Anything sooner seems stalker-esque."

3) Inviting everyone.

Suppose you wake up one morning determined to network with Queen Elizabeth.

"How do you know Elizabeth?" LinkedIn will ask, as if already suspicious.

"Colleague," you say. But when the Queen gets your invitation (which of course she won't), you're in trouble.

If she tells LinkedIn she never heard of you, LinkedIn won't like that. You'll be penalized.

"You need a policy," says Thom Singer, author of several networking books.

"My policy," says Thom, "is The Coffee, Meal or Beer Rule, which means not accepting links unless I've had a real conversation."

4) Bad invitation.

At LinkedIn, the default invite is, "I'd like to add you to my professional network."

But that's robotic.

Eric Fischgrund, Social Media Manager at Beckerman, makes his invites personal. Here are two he successfully sent to CEOs:

"Met your staff at the trade show—looking forward to learning more;" also, "Very interested in SEO companies in the NJ area, and look forward to connecting online."

"My cardinal rule," says Eric: "never use the default."

Tip: For better results, deliver a better invitation.

© Copyright 2011 Paul Hellman. All rights reserved.