"Very truly yours" is the proper form to use when closing a letter. No matter what final phrase is chosen for correspondence, only the first word is capitalized.
The closing is just one part of a friendly letter. It begins with the heading, which includes the writer's address and the date. The greeting, usually "Dear," is followed by the name of the person who is receiving the letter. Next is the body of the letter, which is written in paragraph form and contains all the information the writer wants to include. After the closing comes the writer's signature. Finally, a friendly letter sometimes contains a post script, abbreviated "P.S." This is used when the writer wants to add a final thought.