答案：One possible version:
Dear Katie,
I am happy that you will come to China soon. Now let me share some advice on manners for a family dinner in China with you.
First, you are supposed to arrive on time, or even a few minutes earlier. It is impolite to be late in China. It is also thoughtful to bring a small gift, such as flowers and fruit, to show your respect. Second, when you are at the table, don't tap bowls with chopsticks. It is considered noisy and impolite. Instead, it is polite to praise how tasty the food is. At last, before leaving, be sure to thank the family for their treat. You'd better not stay too long after the meal, for they might have other plans afterwards.
I hope that you find my advice useful and have a good time in China.
Yours,
Wang Yu