Assume for a minute that that best way to take notes is on paper with pens, pencils etc., and not in a digital device. (I might return to this later).
I'm torn between two extremes for note-taking. One one hand, I find it useful in the short-term to make scrappy, ephemeral notes: ad-hoc daily TODO lists; mind maps and experiments, that I intend to throw away. There are lots of styles of stationary to support this: ring-bound notebooks that are easy to tear leaves from; or literally the back of envelopes.
The other extreme is the "preserve everything" mentality. For my PhD, I have a single, hard-backed notebook that I try to do all my PhD note taking in. I date each entry. There's a history I can refer to, no matter whether what I'm writing is seemingly ephemeral or not.
So I do both. Sometimes I want to refer back to something I did which was ephemeral and I've lost it or thrown it away. And having lots of mis-matched stationary for ephemeral storage is a bit messy, and works against the other extreme to a certain extent.
I've started to wonder whether strictly doing one or the other (and most likely, the "preserve everything" approach) might be a good idea. In practise that would mean settling on a particular notebook format, and disposing of anything else; having separate notebooks by topics (PhD, work, …) with a "catch-all" for the rest.
Does anyone have any advice or useful resources to read on this topic?