http://www.ehow.com/how_4561907_of-united-states-of-america.html
1. Organize your thoughts:
Take the time to jot down the general ideas that you want to convey in this letter. What is your subject? What are the facts? What is your opinion? Address only one topic in your letter. If you have additional topics, write an additional letter.
2. Type your letter in the appropriate format:
Use the style of a business letter.
Include the date, your full name and mailing address.
The proper greeting is "Dear Mr. President".
3. Continue your letter in a respectful tone. Use proper grammar, punctuation, and spelling. You want your message to be understood, and taken seriously. Never, ever threaten or harass in your letter. It is ok to express your opinion such as saying that you are upset or angry about a situation. It is NEVER acceptable to use threatening or harassing language. Do not use profanity.
4. Proofreading:
Have someone else read over your letter before you send it. They can often see small mistakes that you have overlooked.
5. Addressing and Mailing:
Use the correct address:
The White House
1600 Pennsylvania Avenue NW
Washington, DC 20500
Use your correct mailing address if you hope to get a response.
Use the appropriate postage:
Use a first class letter rate stamp. How embarassing would it be for your letter to arrive "postage due"?