The first step to gaining this free publicity is to write a press release. You can find instructions for this here. No matter what your product or service is, you need a good press release to start with.
Once you have a really great press release ready to go, you need to know what to do with it. Send the release to the business editors of all your area newspapers and related trade journals.
Write articles related to your business. These should be in "how-to" form. 500-1000 words will be plenty. Send this, for free, to ezines, newsletters, magazines, and newspapers. Make sure you plug your product or service in a small paragraph "About the Author". Getting this article published in these mediums will gain you more exposure than if you had purchased the advertising space. Many people only read the articles...and skip the advertisements.