My system is very unstructured (and I don’t keep these entries in a separate journal, either; they go right in my main one). What I like to do is to write a new entry when I finish a book, which I use as a space to draft the post I will eventually put up on Dreamwidth. I put down the author and title, but nothing else. Sometimes I will write a short entry partway through a book, especially if I want to keep notes about something that I’m afraid I’ll forget by the end, but for most books it is only that one entry at the conclusion.

The important part for me is the practice of taking space to digest my thoughts/feelings on paper. I don’t use prompts. The balance is usually in favor of one or two main themes, or a character/relationship arc, in the book, with enough plot summary in the first or second paragraph to put it all in context. I often end up writing about this book in comparison with other things in the genre or era that I’ve read. I like to think about how my reading fills out what I know, my expectations for tropes, archetypes, plots, etc. I also tend to comment on what worked well for me, and what did not. My goal is to be analytical in my book journaling, but with a focus on the personal (my reactions, my experiences).

Good luck with your new journal! It’s been really fulfilling for me to make a practice of reading professionally published fiction (in addition to fanfic), and I hope that your 2025 bingo goes well. :)