Any tips for my interview today?

I have my second interview today at BonTon. The first one went very well. I was cool, calm, and collected. I gave solid answers and the woman was very friendly. They asked me to come back for a second interview. I’m not sure what the purpose of another interview is? But for some reason I’m a lot more on edge about this one. This time around the lady who will interview me is a tough cookie. I’ve seen her around the store and she seems uptight, and dare I say, mean…How can I win this one over? It’s always hard to keep an upbeat attitude when the person you’re speaking to is so negetive. Any advice?