Here are three suggestions to improve the usability of the tags portal:
1. Do away with story categories, or treat them like tags. It's hard to find stories that could easily fit into two or three categories, because once you click on one category you're excluding a lot of others. If I want to look for Lesbian Fantasy stories, I don't know whether they're filed under Lesbian or Sci-Fi & Fantasy, and the second I click on one I'm losing half of the stories. Categories don't provide anything right now. Tags should replace them entirely.
2. Consolidate similar tags. There are a lot of tags right now that are basically duplicates of each other. As above, if I want stories about elves and click on the "Elves" tag, I don't get the stories that were instead tagged "Elf." There are tons of tags that could be consolidated. For example: Submission/Submissive, Sister/Sisters, Dominance/Dominant/Domination, Exhibitionism/Exhibitionist. You get the idea. In each of these cases, the existence of these duplicates makes it harder to find the right stories because you don't know which tags to search under, and you end up having to search through combinations of all of these tags to find all of the stories you want.
3. Allow the exclusion of tags. It's arguably more important to not get the stories you don't want that to get the ones you do.