Smile, but never smile without crinkling your eyes, that shows insincerity. Be warm and inviting, compliment them but don’t overdo it, never lie. People can tell when you’re lying. If you can’t think of a good compliment compliment the piece you’re selling and add a physical feature. “Oh, that gold necklace is wonderful with your hair color/eyes, they really compliment each other!” One compliment at the beginning when they’re trying it on or when you’re directing them towards a piece and one at the end towards the close or at the close o the sale. Wear some jewelery yourself. No one trusts a salesman/saleswoman who doesn’t sport their own product. And always look your best, hair, make up, clothing. No matter what you’re selling, the better you look the more people take the hint that having what you’ve got will make them better too. It’s basic psych. Be cheery but not overly perky. Try to match the tone and cadence of your customers speech. Those are the things I did. I’ve won a lot of employee awards. A lot.