A reading journal can be as simple as a list of titles and dates. You do not need elaborate reviews, color-coded charts, or a perfect record. Decide what you want the journal to do: help you remember books, collect passages, track recommendations, or notice patterns in your taste. One clear purpose is usually enough to get started.
Use a format that fits your habits. A notebook works well if you enjoy writing by hand; a notes app can be easier to search; a card tucked inside each book keeps thoughts close to the page. For each read, you might record the title, author, format, and a sentence about what stayed with you. Add more only when you genuinely want to.
Instead of scoring every book, try a few prompts. What surprised you? Who might enjoy this? Which passage would you like to remember? Did you abandon it, and what helped you make that decision? These questions preserve useful impressions without asking you to produce a polished review immediately.
Let the journal be incomplete. You may forget to write for weeks, or find that your preferred format changes. Restart whenever you feel like it, and do not backfill entries from memory unless it sounds fun. The best reading record is one you enjoy returning to, whether it grows into a detailed archive or stays a handful of notes.