The biggest pitfall, I find with the free-flowing everything is right and nothing is wrong dictums of mixed media, is that it's far too easy to overdo things.
I do it a lot.
When you draw observationally, you are in a constant state of push and pull with the thing you are referencing. You simply don't have a choice about whether to stop and analyze what you're doing - drawing observationally is a kind of analysis in itself.
When you don't, you have to make yourself stop. Step back. Analyze.
If everything is right simply because it's you, you have no criteria to use to decide whether you should or should not do something.
It's true that an art journal should be a place of experimentation - but for me, it's also a place to learn lessons, to make mistakes and also to learn how mistakes were made so that not making them repeatedly becomes habitual.
So this is a spread at midpoint. I have a few regrets in it already - that's OK - but it's a good time to take a breath and listen and look.