Write the topic of the note on the index line, and store them sorted. If a card connects multiple topics, pick one and make cross-reference cards that point to the topic with the actual note.
The act of filing new notes will force you to at least glance at your old ones, which can generate serendipitous mental connections. You'll also see when you have multiple cards covering the same topic, which helps to link disparate facts about the same thing together in your head.
Something I try to do is keep my physical notecard files small. Besides the inbox file, urgent and important notecards are the only ones I keep in a physical file.
It's surprising how fast you can go through a thousand notecards. So effective filing is a must. And for me, that means maintaining digital archives. Something that, on its own, is a whole topic for discussion. Once again, I recommend GTD by David Allen if you'd like to dive deeper and avoid reinventing the wheel.
GTD's a wonderful system for keeping track of things you should be doing, but I find his filing system for everything else to be a bit lacking. I've supplemented it with ideas from The Card Index System¹, traditional library card catalogs, and Umberto Eco's recommendations in How to Write a Thesis. At the moment, my card index fills most of my center desk drawer. It may outgrow that soon, but I have no intention of culling it down; it's quite literally an index into my own memories, to help me remember things.
Yes, I agree that GTD isn't a one-size-fits-all solution.
David Allen, in GTD, recommends an alphabetized system. Something that I don't do because all of my reference material is digitized and easily searchable.
Search-ability is the primary reason I avoid keeping a large physical file system.
I take inspiration from multiple books written about productivity and organization. Other books that have been highly influential in my systems are:
- Principles (Dalio)
- The ONE Thing (Keller)
- Organize Tomorrow Today (Selk, Bartow)
- Productivity Planner (more of a journal than a book)
Interestingly, it's the lack of searchability that made me gravitate towards a physical system. It forces me to think about the situations I may find myself in when I'll want a piece of information, in order to file it in the correct place.
This has the odd effect that I'm more successful at finding things in my paper system than I ever was with an electronic one, though it's probably of little use to anyone else. I also find that flipping through the notecards to file or look up something serves as a pretty good idea-generation engine.
Put them in an inbox immediately after writing on the notecard.
At a predetermined time, manage the inbox.
Some of my notecards get stored into folders created for current projects. These folders can be digitized at a later date for archiving and searching. Though, most notecards don't make it that far.
Some notecards represent tasks. Those get recycled as soon as they are completed.
Many notecards head straight to the recycling bin. You'd be surprised how often something seems like a good idea before you write it down.
Most of my process follows the "Getting Things Done"(GTD) framework by David Allen. I highly recommend it.
The act of filing new notes will force you to at least glance at your old ones, which can generate serendipitous mental connections. You'll also see when you have multiple cards covering the same topic, which helps to link disparate facts about the same thing together in your head.