I have a sales job interview and need advice?

Researching the company is excellent. Find out which products are most successful. Be able to talk intelligently on the main products. Most of all have confidence. LOOK the part. Be respectful, answer all questions with a sir or ma'am. Maintain eye contact, smile, and speak clearly. Ask intelligent questions. Find out all you can about the company, it may not be a place you want to work--things like health care, compensation (if not addressed). Also very important is to be punctual. And prepared. Have your own pen for instance, wear a watch.