Start:

1. How is it going? How are you doing recently?

2.I am glad to receive your letter. I am glad to receive your letter.

3. You asked me about (problem question, etc.), now let me give you some advice. You asked me in your letter...., now, let me give you some advice.

4. It has been a long time since we met. We have not seen each other for a long time

Ending:

1.I am looking forward to receiving your letter .I look forward to hearing from you.

2.Thank you in advance. Thank you in advance.

3.Please wirte to me as soon as possible. Please reply as soon as possible

4.Good luck |Best wishes. I wish you good luck

These are We usually memorize it, hope it helps.