When writing radio ads, remember the KISS Principle — Keep It Simple Stu--- (you know the rest).
A radio spot flies by fast. It can't be reviewed or replayed at will. So, your radio ad is no place to recite a laundry list of product features or business blather. Your ad must grab the listener's attention, make a relevant offer, and generate a phone call or visit. Focus on one idea and drive it home.
When there's a choice between 30 seconds and 60 seconds, opt for 60 seconds. You'll have twice as long to establish your scene, sell your product, and repeat your phone number at least twice. And a 60-second spot doesn't cost much more than a 30 second one.