Instead of dividing this into points which are elaborated on, I'm going to divide this by different sections of the class. No, not like geometry and algebra and arithmetic, that wouldn't really be insanity, would it?
1. Beginning of term
What most people do: Resolve to pay attention, do readings, complete homework, etc. Attempt to take notes. Listen to the teacher rant about "class rules".
What you should do: Read through all and any textbooks, notes, etc. that you have. Evaluate the class in terms of difficulty and remember it can always be easy, except maths. Evaluate the teacher and decide how much attention you want to pay, normally ranging from none to 20%. Identify diligent and kind classmate to borrow notes from.
Acts of procrastination: Daydreaming, doodling on textbooks.
2. The middle period when exams are ages away
What most people do: Do everything in class but listen. Hand in homework late. Incur the wrath of the teacher.
What you should do: Pay the amount of attention designated above, which will be more than your classmates. Copy notes from identified diligent and kind classmate. Know that you understand what the material is about because you have read it and, contrary to what teachers think, are literate. Complete homework in class.
Acts of procrastination: Playing on phones, dozing, chatting. Anything so long as you don't get yelled at too severely.
3. Right before exams
What most people do: Study in class. Freak out.
What you should do: Double the amount of attention you pay, so you won't miss exam tips. Study according to my guide. Relax. You read this blog, you're gonna be fine.
Acts of procrastination: Try to avoid it, but if you have to, just avoid Tumblr.
And there you are: simple, sweet methods to get you through class without flunking the subject.