There's other stuff that you'll write down because you're going to want to refer to it later. (For example, contact information, websites urls, things to put on a to-do list.) I came up with a simple set of margin icons ("@" for contact info, "w" for a www url, a checkbox for a to-do item, the date for an item for your calendar.
If you put them in the margin, then you can cross them off when you put them in your contact list, your calendar, or your to-do list.
You can extend this further with other margin icons. For instance, you can write "M" in the margin to identify meeting notes. or "Q" for a particularly good quote.
The key to note taking is to figure out how you would need the information later and improve the way you capture to support the way you consume.
I was afraid of that. :) But yes, I see your point. I suppose it's hard to do better than: think of what your future self would need to know, providing both context (to jog your memory when possible), rationale (because that is NOT always obvious), and technical detail (both because that stuff changes and because it's better not to re-derive your previous understanding from scratch whenever possible).