The most effective salespeople are friendly, confident and knowledgeable.
One of my pet peeves is that we call our places of business "showrooms" - a term I really think is inappropriate. Aren't they really "selling rooms"? You don't spend hundreds of thousands of dollars building displays and environments only to show your products. You invest your money so you can sell the products you display.
Once the big investment in your "selling room" is completed and people are hired to sell, shouldn't you spend a little more to teach your staff how to sell?