[解析]
Dear Jack,
I am glad to know you are coming to Xi'an with your family. Now I'd like to offer you some advice.(欢迎他和家人来西安旅游)
It's a good idea for you to make preparations. Firstly, try to learn some local culture and traditions,which can help you behave properly during your stay. (高分句型一)Secondly, you'd better know how to use Chinese chopsticks so that you can taste all kinds of food. Besides, if you can speak some Chinese, it will be easier for you to communicate with the people wherever you go.(高分句型二)(提出具体建议并给出理由)
I hope you will find my advice helpful.(希望)
Yours,
Li Hua