"When you're done talking, stop"

Fallows is worth reading.

I have been in sales a number of different times in my career. Silence is an especially valuable tool when selling , for pretty much the same reason.

Clients are uncomfortable with the quiet and want to fill the air. We always said, "Whoever talks first loses" but it isn't quite as simple as that. People will tell you things (if you just shut up!) when given the chance. Silence is the best way to handle it.