Relax, don't think to much about it and ask questions. depending on who your talking to will lead your convo where it has to go & don't worry about what they think because your just going to stress out have fun with it :)
Just have one of your friends introduce you, then you can say hi. Ask him/her questions like how is school going, or like do you know....so and so.... Good luck! I am working on the same thing right now!