怎樣寫一個開頭of a letter to friend???

Dearxxx(your friend's name),
How are you ?Everything it's fine with me.(Introuduce yourself)
(Write about what you want to tell him/her)
(Ask some questions that you want to know about him/her)





Best wishes,
your friend,
(your name)

Dear Polly,
.................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................
Love,
Coco

i think, just treat it naturally by saying:
Dear XXX
Hi! XXX, how's you're going?/How are you?(very formally)It's going fine for me .