1. Keyword Research
First of all, you need to study the keywords you want to rank your product. Obviously, the more searches a given keyword has, the more difficult it will be to position your product, while if it has few searches, your product will be able to stand out in a much higher position, but it may have many fewer visits.
There is virtue in balance. Ideally, you should find keywords that have an acceptable number of visits but that, at the same time, do not have too much competition. This way, you ensure a good position in Amazon's SEO, and it is more likely that you will be able to close a sale.
In addition, it is important to take care of your secondary keywords and longtails, i.e. very specific search terms (usually with a multi-word phrase). For example, you can rank for a generic keyword such as "running shoes", but it will be much more difficult for your product to rank high than if you do it for "marathon running shoes".