Organize yourself, put more effort into your studying, spend less time doing other thing, shit like that.
How about this, instead of stopping when you think you have the material down read through the chapter again. You know when there's that little bit of doubt in the back of your mind saying that you don't understand everything? If you get that, compare your knowledge with someone else and solve some problems at the back of the chapters that you were assigned to shove into your increasingly taxed brain.
That's how you get a A. Or you could just remember everything that you see and hear like some autistic fuckers that I know.