This video is full of useful information on how to optimize your game description and tags to get more sales:
The main takeaway about tagging is that you should remove generic tags and only leave tags specific to your game. So, for example, remove the tag “Indie” as it doesn’t say much about your game and there are hundreds of games that are “Indie”.
The same applies to tagging designs. TeePublic has a post about optimizing tags. Don’t use vague tags like “Art” or “Design”, look instead for words that describe your specific design.