Amazon will not allow you to place a B&N link in the back matter of books sold on their site. (parajunkee.com)
Set up an account at an email marketing site such as MailChimp, then add the link to your signup page in the back matter of your book. (blog.infinitypublishing.com)
Ask for Reviews There are three items constantly jostling for dominance in the back matter of my books: 1) a polite request for a review, with a link, 2) a link to subscribe to my author newsletter, and 3) a description and link to my other works. (susankayequinn.com)