Finishing a notebook is satisfying, but its useful pages can disappear into a shelf. A small amount of indexing makes it easier to return to a recipe idea, a sentence, a drawing or a question you want to keep thinking about.
Choose what is worth finding
Flip through the book once. Mark a handful of pages you might want again. Do not summarise everything; look for the notes that would save you time or give you a useful starting point.
Write a short list on the inside cover or a separate slip: page number, subject, and a few words about why it matters. If the pages have no numbers, add them only where you need them.
Give the book a clear label
Add a date range and a plain description of its contents. A small label on the spine or cover makes it easier to tell similar notebooks apart. Use a label you can remove if you are concerned about marking the cover.
Store books upright or flat in a dry place, away from direct sunlight. Keep especially private material somewhere with access appropriate to its contents.
Carry forward only what needs action
Copy a live question, an unfinished task or a useful reference into the next book. Leave completed notes where they are. Moving everything can turn a fresh notebook into a second archive before it has begun.
The index is a way back, not another project to maintain. If a few words are enough to find a page, they are enough.