some people are a little shy at first when they meet new people. it takes a little time for you to be relaxed enough to open up a little, and once you do, it makes it easier to have good conversations :)
Just pretend, the worse that can go wrong is that the conversation won't go anywhere, but just talk about the random-est things and you'll be fine, as long as you don't over think it. :)
Pretend they arnt wearing any clothes.