1. First, you make sure you do it on your FB page -- because we don't think it works on your profile posts because it's basically direct promotion and that's what pages are for... (could be wrong -- haven't tried it on the profile side)
2. You copy the full amazon link of your book into the place where it says: "What have you been up to lately" It won't work if you put a shortened Amazon link. It has to be the full link -- and if you do multiple posts -- it has to be a slightly different one each time. We find out book via keywords, so that's no problem, because each time the link is slightly different.
3. You wait until Facebook autofills with the book's photo AND the description of your book. Then, you click on the button that will appear that says "UPLOAD IMAGE" -- this is where you can change the auto-filled image of your book's cover to anything you want. We spent $20 on 20 different awesome low res stock images from 123ft.com for a buck each. There are other free image sites you can use as well. Personally, we think you should avoid using images that you don't have the rights to... we know that everyone is doing it on FB. But we think photographers are starting to get clued in... and over-the-long term, you don't want a copyright lawsuit.
4. IMPORTANT: You have to resize the image to be 560 (W) x 292 (H) -- otherwise, this trick will not work. Yes, it takes time to do that with all the photos, and you have to make sure that the photos you pick will be the right resolution and orientation for this... all of that is ---> WORK. For sure. But we think, work that's totally worth it. And once you do it once, it's done and you can also use that resized 560x292 pic on Twitter.
5. Finally, you can modify the auto-fill description below the picture. We remove everything except the title of the book, which is also inherently clickable.
6. At the very top, where you originally put the amazon link, go back and delete the link and replace it with a catchy phrase and hashtags (again, we're planning to post more about this...)
The result? You've now got a clickable customized image that goes directly to your Amazon book page and the book's clickable title underneath the customized photo. It's very elegant and it works.
We no longer put any links in the description. And for months, we've reviewed all the click-through data on the analytics, and it's amazing to watch which photos --paired with which phrases -- get more click-throughs, likes, and better "reach" than others. It really teaches you a ton about what works and what doesn't when attempting to promote your book to its target audience.