How does everyone keep their GM notes organized?
I use Microsoft OneNote with a Notebook for each game I’m running. I have tabs for NPCs with a page for each, Companies and Shops (I play mostly modern/future), Creatures, and one for Adventure notes (one page for each session).
I also add in a tab/pages for a large number of pre-generated names for people, places, and companies for when the need arises. If there are interesting maps, you can also copy them into OneNote for quick reference.
I play mostly online so it is easy to type notes into OneNote during the game.