1 Pre-read the material and perhaps attempt a few problems (if relevant) to see that I understood them. Make preliminary notes and call out places I didn't understand.
2 Prepare a list of questions I had, areas I didn't fully understand - take this to class
3 In class, mostly listen. Annotate my questions to make sure they had been covered (might be a check mark or yes/no might be a short annotation). Ask any I wasn't sure about after they described.
4 The only other things that got written down during lecture were a) logistics (e.g. quiz on X next tuesday, next lecture covers X & Y) or b) new questions or uncertainties to follow up on
5 after the lecture (same day if at all possible) revise the preliminary notes on that lecture into "proper notes" that resolve everything possible
6 If anything isn't resolved, work through it until it is, or hit up office hours, etc.
When lecturing later, I suggested this approach to my classes; many people reported it working well for them.
I would say that by using this approach, particularly by reading ahead a little bit, I cut my over all "study time" nearly in half, mostly because I rarely had to do anything else (that the above) except practice questions for exams - and those went quickly because I had good notes. This got me through a joint honors program with a fair bit of time pressure.