I generally just use these tags:

• TIT2 ／ title
• TPE1／ artist
• TALB ／ album
• TPE2 ／ albumartist - Quod Libet labels this performer.
• TYER ／ date
• TPOS ／ discnumber - If there are multiple
• TCON ／ genre - I have set genres I use, and I also place the country and sometimes city in here.
• TRCK ／ tracknumber
• COMM ／ comment - If I want to specify it's a Youtube rip or something.

Ones that seem neat that I should use:

• TSST ／ discsubtitle
• TLAN ／ language - Fill with three-letter language code from ISO-639-2
  • List of ISO 639-2 codes
  • NB: mul for multiple, zxx for none.
• TSOP ／ artistsort
• TSO2 ／ albumartistsort - Starting to try thee two 'sort' tags now though.
• TSOT ／ titlesort
• TSOA ／ albumsort
• Multiple ones for artist-related URLs.

Maybe notable ones I don't bother with are:

• TCOM ／ composer
• TSOC ／ composersortorder
• MVIN ／ movementnumber
• Shit like play counts and ratings. Though considering a use for ratings.

• https://wiki.hydrogenaud.io/index.php?title=Tag_Mapping