I'll give a little headsup for someone who actually wants information on how to prepare for an interview for this type of job. Every sales/retail interview I've ever had would ask at least one of these two questions...
What does customer service mean to you?
or
How would you rate yourself as far as dependibility is concerned?
They don't care so much about your knowledge of the area because they can train you appropriately. In my experience, here are some good answers to the above questions.
1. Customer service involves 3 steps. First you need to know your customer before they enter the store. If you know the type of customer your area is geared to, you'll be aware of the comments, concerns and questions that they are going to have regarding the product. Next, you need to be able to answer those questions appropriately when the customer enters the store, and guide them. Finally, you need to be able to deal with upset customers.
Obviously, it gets more in depth than that, but that's what I say.
2. Here's what I do for dependibility. I always show up to my interview at least 30 minutes early. You show up, walk around the store and get acquainted (you are gonna work there anyways right?). Then during your interview when they ask you this question you say something like, "I would consider myself very dependable. I am only late due to extreme traffic because I always prepare to be early in case or traffic. Also, I'm so concerned with being on time that I got here 30 minutes early just to make sure I wasn't late for the interview."
You can take those two questions and span it out for another 10 minutes with personal experiences from past jobs, including situations in which you help resolved problems, experiences etc.