I usually search for manga using a category that I'm interested in and find that a lot of manga have small elements of the category. I think adding an option in the category/tag search to only show manga that has the category in its top ten.

That way if I'm using the tag "Character Growth" and I check that option before searching, the result I will get will be manga that has "Character Growth" in high prominence. As opposed to manga that has "Character Growth" in them but isn't the main aspect of the manga.