Don't even try to kiss ass, unless you're really sociable and good at it. I never had to, so I never really tried, but it wouldn't have worked even if I had. For one thing, my attitude is too nonchalant and my manner and body language too abrupt. If I don't respect someone, it'll show through too easily.
However, teachers usually still go out of their way to help me, especially female teachers. It's one of those strange paradox things where men deal with me and think I'm an asshole, but respect my directness, and women deal with me and think I'm really a nice person. Besides that, I have an earnest interest in learning most things, which makes a real difference in how people perceive your motives.
So know yourself before trying to act out of character, and know the teacher too.
The best solution though is to make sure you're on top of your assignments and test preparation at all times. Then you never have to worry about your grades (or math, or social engineering...).