Know your cell phone etiquette. Nothing annoys a professor more than a cell phone ringing during his lecture. Not only does it annoy the professor, it disrupts the entire class. On a smaller scale, texting takes your focus away from the lecture and your professor notices your lack of attention. This annoys the professor and could affect your grade.
Whine to your roommates, not your professor. If you want any slack in the future, don't whine to your professor about assignments or test scores today. Being professional reflects how serious you are about your education. So when you ask for that extension in an adult way, you might just get it.
Never contact a professor at home unless you have permission. You wouldn't want a professor calling your dorm room to ask you why your paper is late, which means they don't want you calling them to ask about Biology. Make an appointment with your teacher for any out-of-class discussion.
Keep any appointments you make with your professor. Few things make a professor as annoyed as giving up valuable office time waiting for a student who never shows up. If you absolutely cannot make an appointment, call or email to warn them.
Watch your mouth in class. When you speak up in class, you are answering a question or providing constructive criticism. Never speak down to the teacher or other students, or you will be in the professor's black book for the entire semester.