He would start writing to his family and would screw the letter up in frustration.

他一次次开始给家里写信，又一次次懊恼地把信揉成团。

《柯林斯英汉双解大词典》

Most letters start with the greeting "Dear" but you can vary that according to the nature of the letter and the person you're writing it to.

大多数感谢信以“亲爱的”开头，但是你可以根据信的属性和收信人而相应地改变。

youdao

Before you start writing your piece, you must follow several reminders, to make your letter professional and sentimental, leaving a good impression on the company.

可是在下笔之前必须注意一些要点，因为它们能让你的辞职信看上去更专业，更具感情，也会令公司留下更好的印象。

youdao

He said when gay officers had first tried to start their own organisation, there was a "vociferous" letter-writing campaign against it.

BBC: NEWS | UK | England | London | Modernising gay officer gets MBE