No one wants to work with negative people, and there are enough willing technicians out there not to have to. Bringing a positive attitude to class and production work only serves the student in positive ways. A good attitude is conducive to learning and will help you by letting a teacher know you are willing to learn. Be on time. Whether in school or professional theatre, no saying carries more weight.
Punctuality is simply the mark of a professional.
In Los Angeles, it takes special care to make sure you are always on time, but it is a trait considered necessary to function in the world of impossible deadlines. Plus, the attitude from producers is that everything needed to be done yesterday. The Academy policy is that if you are tardy twice or absent once from a crew call, you are removed from the show. Learn by experience. Nothing in the classroom can replace the actual experience of building and mounting productions.