I keep all of what happened in one journal, and everything else on the computer. All the maps, the schedules, and the character sheets using a gurps character sheet program (forgot what its called), because I run it through discord using a text format. I hardly plan anything besides what's in my head.
Ive been trying to use different ways to plan besides just pure vibes. like using joplin, or some wiki format or even trying to do use a mindmap? But alas most of what I do is simulating what I believe would happen and keeping character sheets of possible enemies on hand.
I use the superior method, a mess of illegible scribblings in a journal. I am trying to get better about it, though. And one thing im really trying to do is focus my prep on what the region is like, and what the important actors there are doing, and not on what i think the players will do. Every time I try to predict the pc actions they completely flip my prep on its head, so I want to go for more of an "informed improv" type prep
I felt the illegible scribblings in a journal because thats what I did when I was first starting to layout the setting. Even my maps look like that. I drew most of it in tuxpaint for that deranged feeling 🫣
I think that planning and keeping in mind what NPCs do through out makes the game feel "alive". I try to do something like that, though I'm not sure how good I am at it. At most I just make recurring characters appear where they might be when a player enters a building or a setting occasionally