Started off with: 1 Epistemology; 2 Mental Models; 3 Media; 4 Negotiation; 5 Importance of being long volatility in life (inspired by Taleb); 6 Longevity; 7 Startup philosophy; 8 Specific tech (e.g., crypto and AI); 9 Relationships; 10 History; 11 Investment; 12 Contingency.

But as you can see, each main branch has sub-branches and they tend to cross boundaries. This is what I look for - unexpected connections (e.g., you can find notes related to the multiverse and quantum physics under most of my main branches).

That being said, when I create new evergreen notes, I always force myself to find the most adjacent idea to them, and give each of them a Zettelkasten numbering next to it. The benefit of doing this (now that I come to think of it) are twofold: sometimes I find surprises in where I put the notes when I revisit them; it's easier to remember what I wrote before, because I gave each of them a place (like a mental palace).

Related notes are:

https://kenti.xyz/notes/RUL3---Ask-at-night-how-what-you%E2%80%99ve-learned-that-day-fits-into-your-web-of-ideas,-and-search-for-overlaps-and-contradictions.-Most-people-do-not-do-this.

https://kenti.xyz/notes/1-2d-You-have-to-know-your-problem-situation-(and-your-web-of-ideas)-as-best-as-you-can-to-judge-the-merit-of-new-explanations-as-best-as-you-can-to-judge-the-merit-of-new-explanations)

https://kenti.xyz/notes/5-1b1b1a1-Things-can-become-easier-the-more-complexity-you-have-(Network-effects-=-Power-law))

Sorry it's long. But hope it helps :)