Just like in the Face to Face setting, guidelines are necessary for both the student and the teacher to be successful in the class.  Procedures and guidelines for best practices must be communicated effectively from the beginning of the course and be accessable to students throughout the course via a syllabus or Code of Conduct.  I have found that posting, sharing, and reminding students is essential for them to get in the pattern, get in the routine of how the classroom - on line or face to face - in order for there to be a strong community of learners in the classroom.