The key to note-taking, at least for me, was to stop worrying about things like hierarchy, file structure, file type, and which editor to use, and to actually start capturing my notes. We have (I hope all of us) decades to worry about these things. But ideas and random thoughts will go as fast as they come to mind. Do you have a CS background or any familiarity with terminal stuff? Initialize a Git repo, take your favorite text editor, and create a new note for everything that comes to mind. Otherwise, use any backup or cloud storage you like and trust for syncing.