I usually don’t stick with productivity schemes for long, but I finally found one that seems to work for me: Bullet Journal. It replaced all my list-making and note-taking apps.
It basically helps you to organize your pen-and-paper note-taking. It provides guidance and avoids confusion, but it is not too over-structured, so you are still free to take notes as you want and you won’t have to stick to particular procedures (like with GTD).
Have a look at the video, it is actually enjoyable and gives you a good overview of the system. (This also is a first, I’m usually a text person.)