Best advice...be cooperative and enthusiastic.
If you tell someone you are going to get back to them on something that you had to look up, make sure you actually do get back to them.
Respect everyone you come in contact with...patients, preceptors, pharmacy staff, other staff.
Don't complain.
Actively participate in what you're doing.
Don't come late or leave early (unless they tell you to go home!).
Understand that a preceptor also has to do their job..so don't take it personally if they can't spend every second of your rotation with them.
Take advantage of every opportunity there is to learn something at a site. You'll get out of the rotation the effort you put into it.
Most of all...smile and be friendly.