Turn your cell phone OFF. In the US, a dealbuster for us is clients answering their cellphone and yapping away during dinner. Even putting the phone on vibrate is annoying because s/he is always looking down at who is calling. If it's a family situation, no problem.
I can't tell you how many people we've decided not to do business with, and I suspect a few are on this board, based on some of the responses in the "Woman on the cell phone" thread in "Dining".
