What I taught as a marketing instructor at Cleveland State University a few years ago still holds true today - you need to create a consistent effort using a targeted media mix where each effort reinforces itself. Or, put another way, Don't Put all Your Eggs Into One Basket. Online marketers have discovered they need traditional media in order to drive prospects to their sites. Another key here is to always test whichever media you are using for its effectiveness with different groups you are targeting. Radio, for instance, is a tough way to go for a few simple reasons.
Radio is heard by the majority of people while driving to and from work each day.
Further, newspapers have a high degree of trust which has been fostered among its readers throughout the years. The National Newspaper Association recently issued a report that found Internet users are still twice as likely to read or use a traditional print classified ad than a similar ad online. Nearly all newspapers and magazines now include regular columns devoted to 'what's new on the net. These same services can even place inexpensive classified ads in virtually every newspaper in the country for you at a substantial savings. While the following isn't comprehensive, it will provide you with plenty of idea starters as to how you can promote your URL without choking your wallet.