AP refers to the Associated Press, an organization responsible for setting the rules and regulations for print news writing style. While AP is not the only organization with news guidelines -- the New York Times has its own, for example -- the AP's rules are the most commonly used. For consistency, AP has rules for press releases as well.
Cover the five Ws: Who, What, When, Where, and Why. A press release functions as the hook to get an editor’s attention. However, even if you have her attention, if you do not cover the necessary information, she will still find something else to print. The five Ws tell the editor the importance of the information presented.
Start with your main point. In journalistic writing, the main point, or overall topic, needs to be at the beginning. If the editor has to dig for it, he will find some other press release to print. You can also underline your main point by including a sample headline.
Look carefully at your use of dates and numbers. For example, ordinal numbers first through ninth have to be spelled out, while anything 10th and over uses numerals. the same applies for cardinal numbers one through nine, with 10 and higher written as numerals. Dates and years use numerals. All months with more than five letters, such as January, are expected to be abbreviated.
Go over your punctuation. It is important to remember to use one space after the period. Also commas and periods go inside of quotation marks, and serial commas are not used. That is, if you have a list of items, you do not need a comma before the last item: "This is a list of one, two and three items." Some writing styles do require a comma after the "and."
Check names and titles. The first time a person is introduced, you must use her first name and full title. Formal titles, such as President or Senator, must be capitalized and appear before the person’s name. Informal titles such as deputy secretary of government agency are in lowercase and can appear either before or after a person’s name. After first use, only the last name is necessary, except in cases where two people have the same last name or the name is mentioned in a direct quotation.
Double check and double space. When you finish writing your press release, double space the body of the release in order to give the editor space to edit the piece as necessary. Also, double check all your facts, including grammar and spelling, to ensure you are putting the best possible face on your company.