What do you consider is the most important when working with customers?

Making them happy of course. Making sure they get exactly what they need and then exceeding their expectations!

Eye contact, presentation, proper mannerisms (sir, ma'am, etc.), etiquette, and knowledge of the product or company that you're representing. Listen to what they want and cater to their needs and you'll be just fine. (Treat others the way you would like to be treated). As hard as it will be with certain rude people, try not to lose your composure and be disrespectful. I've been fired from a few jobs for being a step away from slugging a few customers that really needed to be hit by a speeding train.

courtesy and patience......the will to satisfy them and the courage to say that the customer is always right........

Be friendly, honest, patient and listen well.

A good working knowledge of the product they are looking to buy and excellent ability to demonstrate product. Be respectful and not pushy.

Depends what field you are talking about...but just to be friendly and present with them

put yourself in their shoes - how would you like to be treated and dont assume they know anything about anything

Listening and responding to their needs properly.

Good Communication...