How to be the life of a party? For teenagers?

I am going to a little beach party in a few days and I'm a little bit nervous. My best friend is going to be there, but I'm not really good friends with anyone else and I'm a pretty shy person. I think these people like me because they invited me, but I just don't know them that well. I want to be great friends with them, but I usually get shy and don't know what to say. How can I be myself and be the life of the party. BTW my best friend is very good friends with all of these people, but I don't want to depend on him to have fun because he will want to be talking to everyone, not just me. There will also be a girl there who makes me feel kind of intimidated which makes my situation harder. What can I do to just loosen up and make new friends?