Some executives turn to LinkedIn to screen job candidates. Others rely on the professional social network to generate sales leads. And still others use it -- or some of its 225 million members--to make connections.

If, at one point or another, you'd like to do the latter, we recommend following the advice of Carol Ross. Ross, a former Bell Labs engineer who runs the blog Break Out of Your Bubble, demonstrates how to ask for a LinkedIn introduction in a post on Forbes.com. She offers this sample request, in the form of an e-mail, and four corresponding rules.

Sample Introduction Request

Subject: Following up on your thoughtful advice on clothing companies [Rule 1]

Hi Rick,

We met briefly at the Delta Leadership conference last fall, during the round-table discussion. [Rule 2] To refresh your memory, I am changing careers, from being an accountant to being a fashion merchandiser. You were kind enough to give me advice on companies that might appreciate my background.

Since we last spoke, I've decided it would be helpful to get online clothing company experience. Acme Shoes is one of the companies I admire in the online world, and I noticed that you have a first-degree connection to Ellen Jones, a marketing director there. [Rule 3]

Would you be willing to introduce me to Ellen? If you feel uncomfortable making an introduction, no worries. Alternatively, I would appreciate any advice you have on how best to approach Ellen.

Any help you could provide before the end of the month would be greatly appreciated. [Rule 4] Thank you, and I hope to hear from you soon!

Wendy Perez

Ross's Rules for Requesting an Introduction

Rule 1: Create an intriguing subject line. 
"In addition to stirring someone's curiosity, subject lines should be relevant," notes Ross. "Make yours personal. Add humor if that fits with your personality. Here's an example of a great subject line: 'Finally, taking you up on your sage advice!' And here's an example of a clunker: 'Need an introduction.'"

Rule 2: Make sure it's clear how you and the person who'll introduce you know each other. 
"Your message could start off with something as simple as: 'We met last year at the Pegasus conference during the financial modeling breakout session. I enjoyed our conversation about big data,'" Ross writes.

Rule 3: Be as specific as possible about why you're asking for the introduction.
"Talk about why connecting to the particular person could help you reach your goals and why you decided to ask the person who's receiving your request," Ross advises.

Rule 4: Be gracious. 
"Soften any deadlines you may have with wording such as: 'It would be really helpful to me if you could provide your response by [date].' People will respond to an invitation more than a demand," Ross says. Observe, too, that Wendy gives Rick permission to decline her request.

One other thing to keep in mind: The sought-after contact, Ellen, is a second-degree connection to the writer, Wendy. Which means, in LinkedIn parlance, that Ellen and Wendy share a LinkedIn connection in Rick.

Ross suggests limiting your requests for introductions to these second-degree connections, as opposed to third-degree connections (wherein the recipient of your note doesn't know the sought-after contact but knows someone who does). For an explanation why, and to read Ross's rules for following up, read her full post.

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