expresions for letters

Dear Sir/Madam:begin a letter to someone you do not know

Yours sinceresly:finish a letter to someone you know

Dear Mister/Miss...: start a letter to someone you know

Yours Faithfully:end a letter to someone you do not know

Hi:begin a letter to a friend
Hope to see you soon:finish a letter to a friend

Best regards:end a letter to someone you know