I always keep eye contact. It makes people uncomfortable and is a sign of intense dominance in a way. It definitely gives you the upper hand. You can also control your eyes. For example, friends of mine say I have a "prison stare" when I really want to unnerve the person I am talking to. I think most people, as a general statement of people, really have issues with eye contact. The eyes are the window to the soul and people really don't appreciate being made to feel naked.