Anything you think you’ll forget, and anything you think is important. That’s the easy answer.

I take notes on npc names, jobs, locations and maybe a little bit of info on their personality.

For combat encounters and dungeons I stat out every room and take notes on hallways with important stuff in them. I try to keep notes on where things are in the world (a map helps).


Another option is to get a notebook and let another player record specific events (suggest they take turns, keeps writers cramp down and lets everyone focus on the game), think of it as a adventuring journal. They don’t have to record every twist and turn in the dungeon, just the basic events. (Killed dragon, looted horde, partied afterward).

Just remember, organization will set you free.