For things I use infrequently, having basic notes is helpful...if and only if those notes are in a place where I can find them and for that hand written on paper works best for
me.
Other times, I find the process of taking notes helps me avoid glossing over text under the assumption that I understand it...even if I don't go back to the notes ever.
For programming, I find the most useful technique is typing the code into the computer just like back in the 1980's when magazines were the rage. For me it trumps every other method. It also leads me to dislike example code with external dependencies because it takes me out of the zone.
Good luck.
