Ubersuggest

Ubersuggest is a free tool that you can use to identify keywords for strengthening your SEO. Keywords can be used to set up your SEO keywords on your website and in your blog posts so that when someone googles that word, it may lead them to your website. They can also be used to determine where to place your book on Amazon.

With Ubersuggest you can search on three terms per day with the free version of this tool. It provides hundreds of keywords ranked by Search Volume, Cost per Click (CPC), and SEO difficulty.

Search Volume is the approximate number of searches a particular keyword has in a month.

Cost per Click appears to relate to Search Volume; I would think the more a topic is searched upon, the more costly it is to run an ad on Google with that topic.

SEO difficulty is the estimated competition in a category - the higher the number, the more competitive it is.

When setting up your book on Amazon, use these keywords to place your book in categories that bring back about 1,000 results. This indicates interest but allows your book to rise to the top of the rankings, resulting in more exposure.