Identify the radio and or television shows you would like to be interviewed on. Listen to those programs so you can get an idea of the interviewing style of the host. Find out the kind of topics he or she tends to focus on to see if you would be a good fit for their show. The worst thing you can do is send an email or media release to someone who focuses on politics and you want to talk about gardening. Also, it certainly doesn’t hurt to let the host know you listened to a particular show and how much you enjoyed it as you pitch yourself as a guest.
Don't limit yourself to just the stations in your immediate area. Make sure you cover as much territory as possible. Remember, radio interviews can be done over the telephone. Another thing: If you know you're going to be on vacation in a particular area on a specific date, contact the stations in that market and let them know you'll be available. You don't have to tell them you're on vacation---just that you'll be in the area. And don't be afraid to hype up the fact that the Host is getting a great opportunity to interview you.
Know the News of the Day: By knowing what's happening in and around your world, you should figure out how you can tie in your book---especially if you're a non-fiction author. For example: If there's a school shooting in your community and you've written a book young people and crime, call all of the media outlets and offer yourself as an expert.