Jay Levinson, father of Guerrilla Marketing,  emails with some good points the voice actor should always be mindful of:

Marketing is the art of getting people to change their minds – or maintain their mindset if they’re inclined to do business with you already. They either must switch brands or purchase a type of product or service that has never existed before.   That’s asking a lot of them.   Every little thing you do and show and say – not just your advertising or your website – is going to affect people’s perceptions of you.

In other words, in addition to your performance, how you behave and what you say at a session says a lot about you. And remember, you are the product and the brand of your business.