Maybe try checking out the community challenge spreadsheet? I found it overwhelming at first, but there's a ton of great one-off nominated tags in there that might inspire you. Also, posting a fic with those tags would be working towards the community challenge, if you find that motivating.
Re: Trick or Treat!
https://docs.google.com/spreadsheets/d/1mAuxY7LrIbu9fl07N95LHQvS1igj9dQFdJ-NMNR7YII/edit#gid=0