My husband was very introverted before I met him. We used to do an exercise that helped him in social situations. Before we went anywhere, we would come up with three things that he can talk about that are going on in his life. In a recruitment situation, you could do that as well as come up with three things you might want to know more about sorority life or the chapter. These topics are like a tool box that you can draw from if you get nervous and conversation lags. I have a feeling that since you now have a connection to the group though, you'll do just fine. Good luck!
