Decide if the letter should be formal or informal. If the recipient is a friend or relative, your letter will most surely be informal. If the recipient is a business contact, or you do not know him personally, it will most likely be a formal letter.
Decide whether to hand-write or type the letter. Informal letters usually call for simple pen and paper, although typewritten letters may be acceptable. Formal letters should be typed or computer-generated.
Write or type the address heading (the writer's address). Informal letters do not require this step; likewise, if you have your own letterhead stationery, you may skip this step.
Write or type the day, month and year.
Write or type the inside address (the recipient's full name and address). Take care to correctly address the person whom you are writing to; if the person is the president of a company, for example, or a judge, dean, priest, etc., make sure you state the full title. Informal letters do not require an inside address.
Write or type the greeting or salutation. This should correctly address the person you are writing to. "Dear John" would be fine for an informal letter, but the standard "Dear Mr./Ms./Mrs." should be used for formal letters, unless the formal letter is directed to a person holding a special title.
Write or type the body (the content of your letter).
Write or type the closing and signature. Some standard closing phrases include "All my best," "Regards," and "Sincerely." There are no set rules for the informal standard letter, but formal standard letters should have an appropriate closing that matches the purpose of the letter, and that is respectful of the recipient's title or social stature. For a formal letter, skip three lines and type the writer's full name, including any titles.
For printed letters, print the letter and sign it in the space between the closing phrase and the writer's name. For handwritten letters, simply sign the letter.