Avoid eye contact, they will not like it because they do not know you. Instead try focusing on the wall behind them, out a window, or at the floor. As you continue you can begin including short glances at their face, but make sure it's quick or else you will make them start to feel uncomfortable.
First you need to assuage any potential fear they would have of you, so I usually just begin with "I am not planning on robbing. killing, raping, or doing anything similarly negative to you. I'm Pete."
Make sure they can’t get away. Bear traps are effective but costly, I prefer a combination of sleeping gas and laxatives injected directly into the brain stem.
I normally asked them to tell me something about themselves. Since it takes away the pressure from me to break the ice. Plus you can get a pretty good psychological profile about the person based on what they decided to tell you about themselves first.