Ill second what edgepflow said; I think staying up to date with all of your units makes things a hell of a lot easier when it comes to exam time. I see so many people at my university who do hardly any work during semester, and when it comes time for exams, they all panic and end up with very average (or fail) scores.
I like to take it a step further and where possible, stay ahead of the course material by reading before attending the lectures. There are some stages during the semester where the workload is pretty big and it is very difficult to stay ahead, but when possible, it does make things easier. It means you can actually understand most things what the lecturer is saying, and the lectures become a tool for filling in the blanks rather than introducing a whole new topic, which is pretty overwelming if the lecture moves pretty fast.