Eh heh heh. I am a happy go lucky type of student. I do put effort to study, but I also slack equally as much. So I might not have the right to say this.
But I do get pretty okay grades with all the little efforts I put it. 3.5 GPA (not trying to brag here, sorry. haha)
Erm, in class, I try to listen attentively and put down important notes( when i say important notes, I mean things that you know you usually will forget, or out of textbooks teaching) Talk less and listen more.
Also cracking a joke with classmate about the current teaching topic do help you to remember it most of the time. It also lightens the tension of the stern atmosphere in the class.
Always clarify questions no matter how lame that question can be.
When you know you lack of practice(for calculations/formulars/lab practicals) Do spend a few hours to recap yourself and familiarize yourself to it.
I will spend 1-2weeks before hand to revise on my studies.

hope this helps. Do take breaks during revision. Watch 1 episode of anime(typical 24-25min episode), food break, coffee break or something after 2-4 hours of revision. Your mind need as much rest during these breaks as possible.
Hope this helps?