Quite some years ago when studying Business Administration at Cologne university, I tried a lot of different things to make my learning efforts more effective. One of the most effective things I tried was the following:
During the lectures, I took notes of what the professor said. Every now and then, I went through my notes and marked the most important key words with different colours. I then condensed my notes to the most relevant concepts from the lecture, adding more information from the recommended literature here and there and structuring everything in a meaningful way. A couple of weeks before the exam, I had my handwritten summary ready. I focussed only on learning what was included in the summary which was probably about 70-80% of what the professor had talked about. This helped me a lot to first minimize my learning time and second maximise the outcome (the result of the exam).