2. Don't touch your nose or any body fluids.
3. If you have a sickness, wear a mask.
4. Never stick your chopsticks upright in food (means death) or let anyone else use your chopsticks, give scissors as a gift (means severing ties with someone), or give chrysanthemums (sp?) as a gift (its the flower they give during a funeral). Also don't give anything in 4's. One of the ways to say 4 in japanese is "shi", which means death in a different context.
5. Do remove your shoes when you enter a house and put on slippers. Even when you go to the restroom, make sure you remove those slippers and put on a different pair. Cleanliness is extremely important to the japanese because the Shinto religion requires it, and because of that, its inbred into the culture.
6. Eat whatever is in front of you. Don't question the food unless you're learning Japanese and don't know what it is in the English language.
7. Don't talk about WWII or the Sudo-Japanese war. Just don't talk about war period.
8. Be extremely polite. Anything less than polite will make people disrespect you. Never be a loud tourist. Try to blend into the culture.