The thing to always keep in mind while playing Fett is that you are very intimidating to all of the people standing around you. Use that to your advantage. Exploit it.
You're wearing a suit of weaponry. They can't see your face. All they see is their own frailty and uneasiness reflected back at them.
You are cold.
You are merciless.
You display no emotion.
But always maintain a posture of calm readiness. You don't say much. You don't move much. But you could kill everyone in the room in a matter of seconds if necessary.
Just do what Jeremy Bulloch did...watch "The Good, The Bad, and the Ugly" and imitate Clint Eastwood. 
~Brian
