I view guest blogging, e-mail Q&As that are published on blogs, recorded Zoom and Skype interviews, and other invitations that fall out of the internet and land in my inbox as bonus opportunities for information sharing.I realize, though, that not everybody sees it that way.

Writing a guest post or answering questions for someone else’s blog takes time — and time can be hard to come by.

Guest blogging goes both ways

That applies whether you’re writing for someone else’s site, or you’re inviting a person to write for your site.

In the same way that you might hesitate to write for another site, you might be reluctant to ask someone to make that same commitment to you.

But guest blogging — whether you’re contributing to someone else’s blog or inviting them to contribute to yours — is a powerful book marketing tactic. Here are four reasons why:

1. You will reach people you might not reach on your own.

When you contribute information to someone else’s blog, you’re sharing your message with people in your target audience who might not know about you.

If there’s overlap with some of your other marketing efforts — for example, if some of the people who read that blog also follow you on Twitter and Pinterest — all the better. That boosts your credibility while you get the benefit of message repetition.

2. The person who contributes to your blog will bring their fan base to your site.

When you invite another author to write a guest post or do a Q&A on your blog, the people in that person’s network will follow that author to your site. They’ll learn more about you and possibly become fans of yours, too.

That’s a real two-fer — you get content for your blog that you don’t have to create while you help expand your audience. What blogger doesn’t want or need both?

3. You will create and solidify important relationships that will support your activities over the long run.

Do you think that Nina Amir is my new BFF after inviting me to contribute to her site? You bet she is!

We are now connected in a way that isn’t superficial. I will go out of my way to support her as much as I can as a way to repay her for the opportunity to share information with her followers.

4. Providing Information on your blog from other sources is a reader service.

You’re giving your blog subscribers and followers access to information and insights they might not get elsewhere. Isn’t that the point of your blog?

Any time you can draw in helpful information from other sources, you’re providing your readers and followers with a service. They appreciate that.

Be open to the potential of guest blogging. It could open doors that have been stuck shut; it could expand your reach in new and exciting ways.

And, to become the kind of guest blogger who gets invited back, be sure to download our free Guest Blogging Cheat Sheet. It’s your shortcut to success.

What other reasons to guest blog would you add to the list?

(Editor’s note: This article was first published in October 2012. It has been updated and expanded.)