First Day of Class: Take Attendance
You can print out a roster from UAOnline. The roster may not match who shows up for the first class, so note any additions and absences. It is important to ensure everyone in the class has official registered, prior to the term getting underway.
Students not on the roster should register for the class. If someone on the roster never shows up you can withdraw him/her from the class, or give an F or NB grade.
Take attendance every class. You can put out a sign in sheet, even for students with directory holds. The only complication is that that sheet cannot require student ID numbers. At the end of the semester you will need last attendance date when entering grades of F or NB (no basis).