From bookcovercafe:

2. Amazon’s Author Central

This is an absolute must for every author. Amazon’s Author Central is where buyers and readers can discover more about you without leaving Amazon. Your author information can be found further down the page after the product details and reviews section.

…3. Amazon book page ‘tags’

This is often forgotten by independent authors and publishers. Tags are key words or terms which customers have associated with books (or any product) which help them and other online buyers discover related products to that key word or term. The more tags you have for any one term, the more Amazon’s search algorithm (like Google) will favour your book when that term is used by the shopper during a book or product search.