If you use a paper planner, what else do you put in it besides appointments?

I just got one a few weeks back, and I have a note after each month with bill info (what it is, amount, when it's due and if it's paid), I also keep notes of books started/finished on the proper day and a note in the back with my reading challenge for the year. I was thinking of doing some sort of hydration section each week. I also keep a note of pet related things I need to remember for the fur babies.