I’ve been keeping a notebook for over 14 years, and one of the main things I’ve learned is that your notebook is exactly what you put into it. If you pour yourself into it, it will be a patchwork quilt of your life, thoughts and ideas. A timeline of your progress as an artist, a writer, and as a human. The more you use your notebook, the more it will become an automatic response, rather than a deliberate one. Something happens or you have something to remember? Make it a habit to jot it down, and it’ll become a part of the story your notebook is telling (which is of course your story being told and drawn as it happens).
There is only one rule to how you need to use your notebook, and that it that there are no rules. Accidently draw a terrible drawing? Great! Now turn the page and try another one; the only way to get better is keep going. Leave those drawings alone. There will be a time when you look back at these early drawings with embarrassment, and then later on you will look back at them with a sense of pride at how far you’ve come. You’ll remember the things you felt when you made those drawings, then you’ll work on a new thing.