|Photo by Michael Elliott|
Two ways are through Amazon.com: reviewing and tagging.
If a book gets a certain amount of reviews, Amazon will give it better visibility on their site which will result in better sales.
You could also tag the book. This is close to the bottom of the product page, labeled under 'Tags Customers Associate With This Product'. You can agree with tags already in place or add your own. You're allowed up to 15 tags. This will also give the book better visibility.
So, if there is a small quiet book, *cough* Never Eighteen *cough* that you really enjoyed, consider doing this to help the author get the word out about the book.
Have a great Monday.