My setup is similar to @simonsmark. I use Dropbox so that everything is always available no matter the device. Essentially, the top level Dropbox is my Documents folder. Recently, I’ve turned off iCloud Desktop & Documents Folders and stopped using iCloud Drive. See this post on iCloud problems with sync.
I use a modified version of The PARA Method:
https://fortelabs.co/blog/para/
My organization structure is like this:
1 Projects
2 Areas
3 Work Areas
4 Resources
5 Archive
I reflected for a while on my long-term ‘areas’ that rarely change. For example, Finance, Health, Home, Pets, Writing etc.
I usually change all the app preferences to save files in my preferred folders rather than their defaults.
This setup has worked well (so far) for me.