I'm much more of a writer than an artist, so my journal is mostly descriptions of observations, records of my questions, and how I answered them through further observation or research. It's like a journal of discovery, as well as to record memories of places and birds, flowers, insects, animals I've met. I can open to any page and find joy. The illustrations where there are any are just to aid a verbal description.
So, I'd like to get better at drawing so I can incorporate that element. I'm just starting with pencil sketches. I am so impressed by the watercolor sketches, and hope to someday be able to learn that skill as well.