Join Toastmasters

The best way to make yourself speak in a more confident and relaxed manner is to get practice. You can either pay for voice lessons, or join a group such as Toastmasters that aids people in public speaking, preparing speeches, and omitting the "ums" and pauses. Mur runs the podcasting rig for a friend of hers who is a member of Toastmasters (http://www.toastmasters.org/), and she had to do very little editing when the podcast was done. Her friend was only going from bullet points, but she spoke in a confident and relaxed tone and didn't once say "um." Frankly, it was amazing.

You can likely find more tips on the Internet, but those are the ones that have proved most valuable to us. You will find what works best for you, and you will also find that the most important tip is to gain experience. We all go through the early stumbling recordings. (And if you listen to someone's Episode 1 and they sound perfect, we'll bet cash money that person had previous training in either acting, Toastmasters, or radio. So remember, even they had their clumsy period, only not in podcasting.)