Start with Amazon’s guidance

• Categories: https://kdp.amazon.com/en_US/help/topic/G200652170#choose
• Keywords: https://kdp.amazon.com/en_US/help/topic/G201298500

Deeper insights

• Amazon optimization in 2021: insights from Ingram
• Why it's important to keep your metadata fresh
• For self-pub authors: achieving a better Amazon ranking
• Paid tools for researching Amazon keywords and categories
• Claim your Amazon author page and complete it as fully as possible. More info: https://www.janefriedman.com/amazon-author-central-page/