Recently I have noticed that I built up quite a sizeable unorganized collection of songs I listen to regularly, used to listen to, or situational songs.
Here is my strategy, first I dumped everything into /Unclassified/ (which is also where new music is initially added). From there if I noticed I have more than ~3 songs per artists, I dumped that into /{ArtistName}/ playlist. If the number of songs per artist was large I further split that into /{ArtistName}/{Category}. For example /{ArtistName}/{AlbumName}, /{ArtistName}/Singles New, /{ArtistName}/Singles Old etc..
From there I tried to organize those more for the mood / situation / thematically. This is proving somewhat challenging. To make matters more complicated the music I listen to is split across 4 languages Russian, English, Finnish and Polish. So far the more successful playlists are /Russia/Disco, /Russia/Doomer, /Disco Polo/.
I had a /Chill/ playlist which ended up growing very fast, and as a result a lot of songs in it just didn't belong in the same playlist. So I have split them into /Chill/Laid Back and /Chill/Uplifting but I feel like this isn't it. I think I need /Chill/X, /Chill/Y, /Chill/Z.. but I don't know what the X, Y, Z should be.
Anyway would be very interested to hear how you organize your playlists.