I agree with the postings that say be clear, walk the talk, and be human. I try to set the stage by being clear about my expectations. I've learn that I can' assume students (or anyone else) can read my mind so I have to verbalize using simple and straightforward language. "My expectations from you are...." Then I think it's very important to be a role model. Students are smart! They know how to get around the system and if they see you not living up to your standards, they don't feel the need to do it themselves! And lastly, we are all humans who don't do things 100% of the time. So when there are times when you or the students do not meet expectations it is very important to acknowledge the consequences.