I take notes in class, when I get home I try to do a bunch of problems and work on a more complete version of those notes and then I will from memory write a summarized version of those concepts. If I have the time I'll try to simplify it to the point where it's pretty much a ELI5. I enjoy doing that because I'm very anxious and when the anxiety kicks in it's just very tranquilizing to have some easy and key information to remember and work your way from there.
Everything I do is hand written, it just seems to work a lot better for my memory, except the summarized version which I tend to read on my smartphone when I'm on the bus to college. In general I think that constantly revisiting and working with those concepts is what really works for you to remember something long term.