The most important thing to do is smile and look someone in the eye when you are speaking to them. A smile is very contagious and if you are at ease that will relax the person you are speaking to. It is also very good to have a strong handshake when meeting someone but not one that crushes their hand.
People love to talk about themselves. I would suggest asking them questions and then being a good listener to their answers. It disarms them and makes you likeable.
Smile all of the time and tell impressive facts. Also be smart and coy. You want to impress but you do not want to look evil at any cost. Just be cool.
