Turn up on time be smartly dressed know something bout the company and how you would be prepared to work within that store to the best of your ability.
Dress smart and learn that the most important person is the customer!
Focus on customer service and merchandising experience
Research the company beforehand and have an idea of what you're going to be asked on. Practice having a mock interview with a friend or family member and get back from them.
To just be yourself and be prepared for any questions. Also to have a knowledge of the shop.
Short interviews just talking about yourself and job description.