Be prompt. Arrive before class begins. If you come in late, sit in seiza (kneeling position) by the entrance and wait for permission to join practice.
Always bow when entering or leaving the dojo. This is a way of preparing yourself for training, and being respectful of the dojo.
Junior students are expected to look to seniors for guidance, imitate their behavior, and treat them with respect and consideration.
Senior students are expected to set a good example for juniors, protect them from injury, help them learn, and treat them with respect and consideration.
Behave appropriately in the dojo (literally, "place of the Way"). Remove your shoes before entering. Speak quietly and maintain an attitude appropriate for serious practice. Eating, drinking, chewing gum, and using cell phones are not permitted in the dojo.
Never throw or drop your obi (belt) on the ground, and never wash it. Your obi is a symbol of your spirit.
Never lose your temper during practice.
Pay attention; it is part of your training. Concentrate fully on karatedo while you are in the dojo.
Practice your kihon waza and kata consistently outside of class, even if it is just for a few minutes every day. This is the only way to improve your skill and physical conditioning.
Adopted from http://www.uga.edu/karatedo/protocol.html