It is important to strike up an on-going chit-chat with any person you are photographing. Talk about anything. Laugh; give directions; ask questions. I even talk to myself out loud, just so that the pressure is taken off of my subject. I’ll say things like, “Dang! Try to focus the stinkin’ camera next time Randy!” or, “Geeze, I am so hungry!”
By making chit-chat on the set, I am able to evoke a variety of different facial expressions from my model. They often will start listening to my verbal rambling and forget I am aiming a long lens their way.