It helps to type in the words or phrases that you want to use in Amazon’s search bar to get a list of suggestions. Another approach would be to simply google your keywords to judge the popularity of the topic. There’s also a more direct method, and it involves putting your keywords IN your book title or subtitle.
Don’t forget that Amazon provides quite a few categories designed to be linked to keyword suggestions. These are separated into genres, with the intention of helping your books sales rank. Here are a few:
For the full list, clicker HERE
The better the keywords, the more places you can show up in the Kindle store, which means better chances that your book will be seen.
These might help to land your book in more obscure categories, and better your chances at hitting more top 100 lists in the future!