"Don't flash an immediate smile when you greet someone," says Lowndes. If you do, it appears as if anyone in your line of sight would receive that same smile. Instead, pause and look at the other person's face for a second, and then let a "big, warm, responsive smile flood over your face and overflow into your eyes".
Even though the delay is less than a second, it will convince people your smile is personalised for them.
Sticky Eyes
"Pretend your eyes are glued to your conversation partner's with sticky warm taffy," Lowndes advises. Even after they've finished speaking, don't break eye contact. "When you must look away, do it ever so slowly, stretching the gooey taffy until the tiny string finally breaks."
This technique will help you appear more intelligent and insightful. You can also try counting your conversation partner's blinks.