Imagine if you have a cookbook. Take a good picture of a dish, put that recipe up on your site or blog, and then pin it using that picture. When they click on the picture, it will link it back to your site, and back to the recipe. Make sure that you have a great call to action button on the page somewhere that says BUY MY BOOK!! Of course, you can word it better than that (writing is your thing, after all!) but you get the point.
If you are utilizing your blog to market your book, then find a picture that you can legally use (don’t infringe on copyrights) that represents what your post is about, and pin it! You would be surprised at how quickly these pins can be shared, and by how many people.
Check out this awesome article from Wise Ink, and learn more about how you can effectively use Pinterest, and then give it a shot. What’s the worst thing that could happen? (Make sure that you keep writing and don’t just sit on Pinterest all day. That is the worst thing that could happen. It’s addictive!)