DA Aquamaster:
There is some good stuff already mentioned above.
Never skip class. Ever.
Form relationships with faculty and staff at the university.
And while I don't have research to support it, and not many profs will admit it, essay grades tend to be better when the prof already knows you know the material - you get the benefit of the doubt in situations where you other wise wouldn't.
Ask questions in class. I have noted that many students today seem hesitant to ask questions and that many regard questioning as impolite. If you don't don't agree with something, bring it up or ask for clarification.
Those are some of the things I'm experiencing now that DO WORK. At least for old farts like me they work.
Granted some of the instructors are younger than me so there is no room for intimidation, but the old PhD's have to endure my questions the same.
Study groups are good but not enough. You need to study before getting with them and after.
There is also another important thing, and that is learning. I managed to learn the game of the grades. Almost learned it too good, to the point that now (finishing junior year) I wonder if I'm actually learning the stuff I'm studying or just learning to do what each instructor wants for the A's.
One comment above refered to knowing how your instructor thinks, well it isn't hard at all to do that, you ask what they want and they tell you. Sounds obvious, doesn't it? well ....have you ask your instructor what he/she wants for this coming test? did you understand the answer? if you didn't, did you admit you don't get it? This is no time for appearances, if you don't get it you HAVE TO ASK.
The only time a instructor is allowed to get sick of you is if you ask how to solve logs when the class is about double integrals. For that even your classmates should be allow to smack you. I don't know about your particular case, but just know the stuff below your grade level and ask away on the new material
You are buying a service from your instructors. Do your part but also get the service you are paying for.