I talk a lot in class about the fine art of listening. It is important as you begin to find your way in the voiceover business. You must learn to discern the good from the not as good. This way you will be able to tell when you are improving.
A good friend, Dan Friedman, is an audio engineer, a voice talent and recently an on-camera actor. He just published a blog about the importance of listening.
It isn’t too long, so pop over and read it. Always nice to get another point of view about something. Helps you hone your critical thinking!