Andrew is right. Here are some more tips for you http://hubpages.com/hub/Business-Dining-Etiquette-10-Tips-for-showing-good-manners-over-lunch-or-dinner

1) absolutely show up on time ! A good business relation has the respect of each other time (and money) at its ground. 2) if you are invited don't bring all your family along 3) if you are the guest, choose an appropriate place, where food is good; the place will be perceived as the an extension of your office. 4) very very important: don't pressure your potential client to talk about business while you eat; eating together should be a pleasure, at least for your guest, so allow him to choose the conversation. (An exception to this rule: you decided to eat together just because business is so interesting, and there is no other way to talk about it). plus: all the other usual rules that intelligent and polite primates stick to when they eat sitting at a table instead of grasping juicy fruits dangling from trees' branches.