Music I DJ with I mostly play the same genre of music so I have a few playlists for stuff that is outside of my normal genre.

Then within the stuff I usually play I'll have smart playlists for each key (using the Camelot system so 1A, 1B, 2A, 2B etc)

I have a playlist for each month that has everything I have imported for that month of the year.

Some smart playlists to filter out a specific BPM or BPM range.

Playlists containing all the releases I have from specific labels in case I want to do a label only mix.

A playlist containing all the acapellas I have (I don't use a massive amount) so they are all in the same place to throw over the top of some other stuff if the feeling takes me.

Then I also have some playlists that I will create off the cuff throwing in selected artists that I might want to play at a particular time to capture a certain feel or vibe, then usually they stick around and I come back to them occasionally.

A preparation playlist which is a temp playlist where I'll throw random stuff I want to play that day maybe. Like for example I might have like this months additions and marchs additions to my library so I'll just throw both those playlists in the one preparation playlist to play from so they are all in one list.

My music is organised in alphabetical folders within each folder I have a folder for each artist where all their releases go. If I start getting a lot of stuff from one label or end up buying a label discography I'll make a folder for that label and remove any releases that might be in the individual artists folder and place it in the label one instead.

Then I have one random folder that has a few genre specific folders inside where I collect music from artists that I might just have one or two tracks from so they don't deserve their own artists folder.

When I actually listen to music on Spotify I don't use playlists. I want to listen to albums in the way they were intended, front to back usually, so I'll usually just pick what ever album I want at the time. Occasionally if I want to delve into an unknown to me genre I might search out a playlist made by someone else to explore artists I don't know to give me an idea of what I might want to then pursue listening to further.