Learn two easy skills and make an average sound file seem like it was recorded at a real studio!
Use the equalization tool in Audacity to add depth to what your microphone picked up.  The first time you do this you'll need to spend time experimenting with settings.  Once you've done this you can save your layout and apply it to future recordings.
Here are the settings I use.  Click here to see how you can save your customized settings.
You may need to amplify your sound file so it plays at a consistent level with other audio files your listeners play for themselves.  Again, this is a process which becomes almost automated once you've done it a couple of times.
When you convert your file to mp3 you need to adjust the quality level to save storage space.  If a stereo file sounds good to you at 128 kbps you should be able to save a mono recording at 64 kbps with no dropoff.
This episode was recorded with no script.  I did this so you can see how much more personality you can inject when you're speaking directly to your audience.  You'll notice the drawback is there are some awkward pauses and verbal stumbling.  This is the difference between a talk show and a newscast...or a speech.  Speaking off the cuff also tends to make the presentation longer, because a script regiments your delivery and keeps it more concise.
I'm not preaching one method over the other, they each have their place.  Do what feels right for the effect you're trying to achieve!