I was in retail mgmt. for years, have a b.s. in fashion merchandising...although I never worked for a luxury retailer I've had friends who did and I can tell you that typically this type of company wants someone who has 1. experience in retail sales, preferably luxury, 2. fantastic customer service skills, i.e. selling skills, poise, and composure, and 3. very well-groomed and well mannered. The above poster mentioned that experience in keeping a client book is desired, and this is true, although if you possess other qualities they're looking for you can certainly be trained in that area. Basically what it comes down to is, are you friendly and able to deal with clients who are very discriminating and maintain your composure and professional attitude, and are you able to present yourself well at all times to help the company achieve its bottom line?
If you are granted an interview, ask yourself before going in how you answer certain questions, as far as how you will deal with difficult customers/co-workers. Be prepared to speak about yourself in a positive manner while being modest, and above all, when any question is posed, remember that you will be working for this company to increase sales, bottom line, not to get the discount for yourself and your friends! LOL! I'm sure you have what it takes, and I wish you the best of luck!