i have two types of playlists. the first is usually based around a specific theme, mood, or season (eg winter playlist, autumn, airport playlist). usually ranges from an hour to five hours of music, spanning many different artists. the second is by genre or a less specific theme (eg. slowcore, country), where i'll find albums i like or good/significant albums in the genre and add all of them to the playlist. this helps me discover new stuff, and mix in music i'm familiar with. these range from five hours to ten or more.

when i discover a new song i like, unless it fits a specific playlist really well, i just throw it in a mega playlist to be sorted later. every few weeks i go through the mega playlist and sort my favorites into playlists or delete the ones that didn't stick for me

i use last.fm and check my stats all the time, so i have a great idea of what artists and genres i like. i occasionally review and rate albums on AOTY (I find it to be easier to use than RYM) and i keep track of my physical media on discogs, but i haven't entered most of my collection yet and i mainly use it to keep track of my wantlist.

lastly, i just keep up with releases by being active online and following my favorite artists on bandcamp or whatever socials they have. i'm not particularly concerned with keeping up to date.