When you're giving a speech or presentation, do you stay away from the audience before you start? It's easy enough to do: There's almost always a speaker table, the organizer to talk to, a green room or the audio-visual with which to occupy yourself.  You're about to impart your wisdom, you need some quiet time, you want to focus your thoughts one last time.

Despite all that, there are plenty of top speakers who do exactly the opposite. You'll find them greeting participants as they...