If the interview is over lunch, do not order an alcoholic drink or something that is messy to eat. (Choose a salad rather than a huge layered sandwich.)
Lunch interviews are always tricky – “What should I order? Will I be able to really provide enough information while they are eating, or, more importantly, while I am eating? The first rule is do not order an alcoholic drink, even if the interviewer does. You want to be alert and you want to show your professionalism, which includes not drinking on the job. Make sure you order something you like so you can eat at least a little, but don’t order ribs or messy sandwiches that make it difficult to be neat and professional. I suggest a salad, soup, or simple entrée that is easy to eat and is moderately priced. You don’t want to eat like a bird or a pig, so just take it slow and eat when they are talking. Make sure you do not attend the lunch interview when you are starving because you will not be able to concentrate on the interview! Remember, the real reason you are there is for an interview, not the food.
The advantage of a lunch interview is that it is more casual and less stressful, since there are many others around. You also have the opportunity to be more personal during a lunch interview due to the setting. The interviewer is trying to get to know the real you, but you must still talk about your professional experience, like any other interview, with examples and details.