The job focuses largely on customer service and people skills. So think of examples of times where you dealt with problems and disagreements well, or that demonstrate your ability to keep customers happy (managing expectations, conflict, etc.). Also consider what examples in your life show that you are a trustworthy employee that can handle money and expensive merchandise.
Understand the role your interviewing for. Dress to impress but don’t over do it, it’s a retail job. Think of stories from your school or job experience that aligns with customer service and use those during the q&a.
I am not sure how much things have changed since I had my interview there over 2 years ago however, prepare to answer questions enthusiastically and honestly. They did ask about technological abilities such as working with POS systems but you basically learn all that through training (if hired). Be professional, dress the part, and be yourself. Also, bring a printed form of your resume and ask questions at the end of the interview (no matter how simple they may be). I hope that helps! Good luck!