How do you organize music?

I'm so bad at this.
First I just had a lot of stupid named lists like:
"new" 
"new2014"
"shortlist"
"to sort"
"folder with changing playlists"
etc. etc. 

Like a kid whose room was never neat, I could always find the right song. But I decided I need a different way, this didn't feel good. 
So I started making playlists for occasions:
On the bike
On the train
At work
At home

But thats weird because I might want to listen to same songs whether i'm at home or on the train. But I don't want to sort a song in multiple playlists because jeez, when I find a new song I need to think about all the different occasions I'd like to listen to this song. God forbid I find a new BAND to listen to. 

So, how do you guys do this?
Oh, and also, what do you do with things like Spotify-generated lists that change over time? I don't want someone else to be able to edit the songs in my *permanent* collection.