Wasted my keyword slots for months, here's what I wish someone told me
When I published my first book I treated the 7 keyword boxes like tags. Single words like "Japanese" and "language". Complete waste of the slots. Stuff I've figured out since: Each box takes a whole phrase, up to 50 characters. Something like "learn japanese for beginners" covers every search containing those words in any order, so one good phrase does the work of several tags. Don't repeat anything already in your title or subtitle. Amazon indexes those anyway so you're just burning a slot. Biggest mindset shift for me was searching like a buyer instead of an author. Nobody types your book's name. They type their problem, like "jlpt n5 practice" or "japanese workbook for adults". Also you don't need commas or keyword stuffing, Amazon matches the individual words in a phrase on its own. Best free trick: type your keyword into the Amazon search bar and look at the autocomplete suggestions. That's actual buyer language handed to you. And they're not locked in. If you're invisible after a month, swap out the weakest slots and give it a week. The autocomplete thing alone fixed more for me than everything else put together.