One tip I picked up from David Allen that has stuck with me and I think has made some improvement on how I take notes and process them, is writing a single note on a single piece of paper. At this point I’m not sure if it was in the Getting Things Done book or if it was a separate video that I watched where he described this.
Sometimes when we take physical notes, we have a sheet of paper and we take 2 or 3 notes on a particular topic. A little later we use the same piece of paper to jot down a couple items we need from the store. And maybe later we put checklist of action items we need to do for a project. If this piece of paper ever makes it to your physical inbox, it will be extremely difficult to process it.
This might seem wasteful, and it probably is. But processing your physical inbox is much easier and quicker when you only have one item, or at least only one topic, on a single piece of paper.