Always double space. Use wide margins. Start at least two inches from the top of the page and provide the name and phone number of the person to contact for more information. If the item is for immediate release, say so - using those words in CAPS at the top of the release. Check before you send.
Different editors are responsible for different parts of a publication.
For instance, there's a business editor, a city editor, a features editor, a person responsible for compiling information on upcoming events. Make sure your release is going to the right person before you send ft. Many times information is provided at the end of a regular column about how to send items of interest. A lot of variables affect whether your release runs or doesn't run. Editors make judgment calls daily about what gets in and what doesn't.