"Do you really need 15 note-taking apps or do you need to learn how to use the one already there?"

This hasn't really been updated in over a year but is still very good. I still reference it from time to time. It's not the most well laid out guide and there's still a lot of TBD videos that the author never put in but they're easily found on google. Obviously best set up on a Mac or iPad + keyboard rather than just an iPhone.