Which are the main factors determining sound keyword research on Amazon?

I assume that a fully performing keyword research on Amazon is determined mainly by the factors of keyword relevancy (how closely it’s matching the user’s search request), and the current level of ranking competition (how difficult it will be to rank for). It may seem like a no-brainer, but the main goal of keyword research on Amazon is to find those potentially winning yet still not too popular product search terms and long-tail combinations used by the live shoppers buying over there. But how to make easy ranking progress so that your product listing's online visibility grows like hell? 

There are a couple of ways for you to get on with it:

• Running proactive keyword research using Amazon auto-fill option. That way, you can not only instantly get a big picture of the most effective keyword combinations associated with a product category or a certain item taken separately, but understand what search intent keywords local shoppers are more likely to take for their product search upon being shown auto-suggest options by Amazon's algorithm.
• Identifying the most underestimated keywords. I mean those search terms with a considerably high search volume, yet still relatively low competition. That's why probably there is still an insufficient number of related products on sale which are indexed for that particular keyword for now. As a result, those underestimated yet still fully performing search terms and long-tail combinations can reasonably become your number one priority for the keyword research on Amazon.
• Locating trending keywords currently gaining in popularity. Taken in general, the trending keywords are far not too competitive, at least for the moment. But their most recent gains in the search volume (for example, through the past month) make them definitely worth being considered among the first must-winning targets of your keyword research on Amazon.

Along with profitable keywords and long-tail product search combinations, your own merchant list quality and its optimization are important factors too. I mean that having a profitable pool of keywords is good for you. But getting buy without a proper scheme of product listing optimization will inevitably kill your ecommerce business over time. That’s why you should make sure nothing limits your listing’s exposure to online search. Doing so, I recommend having a double-check on the following factors determining a successful keyword indexing on Amazon:

• The product description should be written in somewhere around 250 words to be backed with a list of five bullet points, each fully descriptive yet still clean and concise.
• Product images are very important too. And not only to guide your visitors to the final decision-making to buy with you, but for the search ranking purposes as well. The thing is that Amazon recognizes a set of supportive visual content as an equally strong factor determining your product listing quality.