Sometimes the most successful way to get on national public radio would be to piggyback on other important events that are happening at the time. That is what the following author did and it worked perfectly for him.

We had this book called Watson and DNA that was a biography of James Watson, the guy who discovered the double helix. About a year ago, it was the 50th anniversary of the double helix, and we were able to use that in our pitch to get the author on several National Public Radio shows. And had it not been that anniversary, I don't think we would have been as successful, probably unless there had been some big genetic discovery.

If you want to find out more ideas about how to get on national public radio besides this we recommend the publication How to Get Booked on National Public Radio.
http://101publicrelations.com/nationalpublicradio.html?utm_source=prideas&utm_content=npr