Oh boy you're in for a trip.

I've adopted #zettelkasten for my personal notes / personal knowledge management for years now and I highly recommend it.

Don't have to go crazy into the weeds. Just use Obsidian (or Roam or something) and try to keep the discipline of:

- notes should be atomic and stand on their own, with deeper topics linked out to their own notes.

- every time you create a new note, make sure to link TO IT from an existing note

- if you are beginning to see a higher-level connection between multiple notes, create a "structure note" that links all of them.

Over time you'll end up with a big fun web.

If you want to go deeper, "How to Take Smart Notes" is the classic recommendation: https://www.soenkeahrens.de/en/takesmartnotes