I keep notes for a lot of things, but my philosophy with journal entries is "anything and everything + how I feel about it."
Sometimes it's about capturing moments. Other times it's about processing my shit, and just like getting it on the page and interrogating it. I'll frequently doodle a rough "mood compass" I've come up with to track where I'm at emotionally - but that's for more extreme moods (good and bad).
Sometimes I just feel like making marks and I'll just scratch out the alphabet or whatever nonsense comes to mind.