It is important to have rules and policies of your class in the syllabus and have them sign a "received syllabus" form so they cannot say they never received it and have no clue about the rules. Making sure all of the rules of the class such as make up policy, attendance policy, class content and expectations are all covered day one so they cannot come later with confusion of the rules. Letting the class know that you are avialable to work with them and to contact you for questions makes them feel more at ease about being nervous taking a new class.