A pair of links about Ira Glass Feb 04 2009
The first is a three-part manifesto from 2004 about how he got his start in radio, how to effectively tell stories, and how to realize when your story isn't working.
Force yourself to do a lot of stories. This is the most important thing you can do. Get yourself in a situation where people are expecting work out of you, or where you simply force yourself to do a certain number of stories every month. Turn the stuff out. Deadlines are your friend.
The Gel Conference just posted a video of Glass speaking at the 2007 conference in which he "describes the elements of a good story".