Entrepreneur.com states, Along with print and TV, radio is one of the most popular forms of conventional, “offline” advertising. It can also be one of the most effective. This is partially because radio is oriented around formats, which gives business owners a big advantage in targeting audiences vs. print or TV.

What’s a format? Think “classic rock” on the FM band and “talk radio” on the AM stations. Odds are your target market is predominantly tuned into one or two specific stations in your metro area. If you can discover which stations those are, you may have found the sweet spot in your marketing.

1. Your target market: Don’t simply choose a station because it’s the one you listen to. Choose the one your customers prefer.

2. Costs: There are two costs you’ll incur when you advertise on the radio. The first is airtime–the time unit(s) your commercials are on air, typically broken down into 30-second, 60-second or 120-second segments (or spots), depending on the station.

3. Schedule: One is “run of station,” or ROS. This means the station will decide when your commercials air as well as the specific time of the day that each commercial will be played. The best way to target is to find out which are the highest quarter-hour listening shares for your target demographic. That way, you are paying for your commercials when the chances are good your target audience is actually listening.

4. The economy of words: s a general rule, 65 to 85 words is the limit for a 30-second commercial. However, be aware that this can vary depending on how many sound effects you use. Also keep in mind that your copy block for a 60-second spot will generally only be 30 to 45 seconds, as you will want at least 10 to 15 seconds at the end to include a call to action, phone number, Yellow Pages mention or web address.

5. Choosing the right sounds. If your want your commercial to stand out from the rest, you need to consider some additional factors regarding voice-overs and sound effects. You may be tempted to voice the commercial, but think again–unless you have a really good voice for radio.

Generally speaking, radio’s ability to target an audience and offer repetition makes it a very effective advertising medium. In fact, some of the most effective campaigns in business history have been “radio-only” ad campaigns.