Be prompt in arriving so your
host can begin on time.
Remove your shoes when entering a Japanese home -- the host will provide slippers to wear.
Drink the entire portion of tea (it will not be large) and eat everything served.
Turn the tea bowl slightly to avoid drinking tea from the front side.
Smoking is generally prohibited in the tea room.
Each implement used in a tea gathering (including scroll, flowers, and food) has been thoughtfully selected by your host and has special meaning. They should be treated as objects of appreciation. Admire them and compliment your host with sincerity. This is the most important responsibility of a guest.
After two or three days, call or write a note of thanks to express your appreciation. This is known as korei or "thanking afterwards."