Radio advertising is an important medium for small businesses that want to reach local customers and prospects, or an audience with special interests, such as classical music or sports. Figures from the Radio Advertising Bureau indicate that radio advertising revenue continues to grow, with the strongest growth for ads on digital radio.

Advertise products that are of interest to a radio audience. Businesses with a local focus such as banks, auto dealers, hairdressers, retailers, plumbers and electricians tend to advertise on radio, according to online publication Inc. Include a reference to your local presence in your commercials, such as “available in your local corner store.” Describe the types of services offered, such as “emergency plumbing services for downtown Phoenix.”

Select a radio station that matches the profile of your target audience. Ask the station for a media kit that provides audience statistics and a detailed profile of listeners based on their age, sex, location, interests, income and occupation. Media kits also include qualitative information on listeners’ interests and purchasing habits. Ask for case studies of campaigns featuring products or services similar to yours. Case studies highlight the benefits of such campaigns, such as increased inquiries or sales following radio ads.

Choose a station that covers the region you want to target. The Radio Advertising Bureau has a membership of more than 6,000 radio stations offering a choice of local, regional or national coverage in the U.S. Ask the station for details about their coverage. Use regional or national radio to drive business to retailers or distributors who stock your products around the country.

Compare the cost of advertising spots on stations that offer you suitable audience and geographical coverage. Use a metric called "cost per point" to identify the best coverage available for your budget. Cost per point is the cost of reaching 1 percent of your target audience within a geographical area. Set a budget that covers the number of ads you plan to run and the cost of producing the commercial.

Choose a time slot in which to run your commercials. Drive times in the morning or late afternoon are popular times to reach an audience that is listening to radio to get the latest news, weather or traffic reports. Choose a run of station spots if you want to make your budget go further. These spots run at any time during the day or night, but will not generally air at the most popular times.

Write a script for your commercial or hire a professional writer. Include a call to action in your commercial, such as “call this number to place your order” or “visit our website to find out more.” Keep the information in the ad and the contact details simple because listeners might be driving or carrying out chores. Ask a recording studio or the radio station to record the commercial. Some radio stations offer a free or low-cost recording service for advertisers.