How To Write A Friendly Letter To A Close Friend . Begin by enquiry of the health of the receiver and their near and dear ones. I was just wondering that we have been friends since the longest times and for all these years; A letter to a friend LearnEnglish Teens British Council from learnenglishteens.britishcouncil.org I have been thinking of writing this letter to you since long. Need help writing a letter? The expressions you use depend on your relationship with the person you are writing to, particularly whether you know her personally.