In the words of Ira Glass, the most crucial thing you can do is a lot of work. Dive in, do the repetitions, and seek opportunities for more.
Almost every city has a community radio station, which is the perfect opportunity for podcasters to do this work. These stations offer invaluable experience for podcasters, since broadcast radio, while similar to podcasting, is very different from podcasting.
KCRW is a Santa Monica-based NPR affiliate that hosts a 24-hour challenge for podcasters and radio producers and is an excellent opportunity for anyone, regardless of location. Participants receive a topic at 10AM Saturday and have until 10AM Sunday to complete a four-minute piece – another rep under your belt in just 24 hours.
Opportunities for "more work" in radio and podcasting are everywhere. You don't have to publish it and it doesn't have to be perfect, but if you show up with intention, you will get better.