There is one major advantage that you get when you make your notes digital and keep them on a computer. You can very easily search through notes for specific words or tags. But with this little hack you can easily create a simple index even if you keep a pocket notebook like a moleskin, a paper journal, or regular old notebooks for writing notes. The tip, which apparently comes from Japan, involves creating an index in your notebook and marking the edge of pages.
For example let’s imagine you’re keeping a notebook for recipes and you just wrote down a Chinese recipe on the first page. Next you’d go to the last page and create the tag ‘Chinese’ by writing it on the first line right next to the papers left edge.
Now you’d go back to the first page where the recipe is and on the exact same line as the ‘Chinese’ label you just wrote you’d make a little mark on the right edge. You’d make this mark so that even when the notepad was closed the mark would be visible. After repeating this for various recipes you’d now have various tags visible on the notebooks edge.
A Little Known Hack From Japan To Get Your Notebook Organized (High Five Blog)