If you look into someone's eyes, they will tend to look to their right when they are remembering or being honest and they will tend to access their creativity by looking up and left or simply left when lying.
Liars tend to blink more, don't know why, perhaps it's the pressure.
A forced smile does not engage the entire face, it's simply moving the muscles of the mouth. A real smile is emotionally engaged and muscles of the entire face come into play.
Someone avoiding the question is often telling the truth, but only because then they don't have to lie. For instance, Did you steal the ring? I've got plenty of money. Or Did you see it happen? I'm just minding my own business.