Before you start production, you have characters you have created without actors in mind, then all of a sudden you've got actors. They bring an enormous amount in creating these characters, and creating the dynamics between the characters that you've written.
I like relaxed sets. I like to feel that I can make a mistake without feeling like I'm costing somebody money. I like a sense of freedom. I like it when people are open and are willing to let you do your work.