Simply put, a guest post is a blog entry written by a person other than the regular author team.
You are not restricted to reading only traditional print periodicals. A great venue for you to advertise your book is on blogs.
If you locate a site that you believe might be a good fit for your book, you must determine whether they accept guest posts.
Some blogs make it quite clear when it comes to accepting guest posts. You may occasionally come upon a “write for us” or “guest posts” page.
Even if there isn’t a clear indication if a site allows guest pieces, it’s still worthwhile to inquire.
When you reach out, avoid using a canned pitch. Spend some time creating a thoughtful, unique expression of interest. Be sincere and focus on the value you can add to the blog.
Any chance you get to guest write should be viewed as a win-win. The blog’s followers should appreciate the post you create, and you should quietly promote your new book in it.