The Flooding Smile
Don’t flash an immediate smile when you greet someone, as though anyone who walked into your line of sight would be the beneficiary. Instead, look at the other person’s face for a second. Pause. Soak in their persona.
Then let a big, warm, responsive smile flood over your face and overflow into your eyes. It will engulf the recipient like a warm wave. The split-second delay convinces people your flooding smile is genuine and only for them.
– "How to talk to anyone" By Leil Lowndes
Get your hands on this book…not great but a good read..tips such as above give us an insight into humane psyche.