Look for color, the more color the better, specifically around the vegetables. Meats and Carbohydrates usually come in brown tones, you get your color from your vegetables. Salads and seasonal veggies are perfect. Also, when ordering a salad, ask for the dressing on the side, then don't use all of it. Also, try to avoid dinners that have a large amount of sauce in them.
You can also ask for the meal to be cooked with less fat in them. Chef are more than willing to accommodate virtually everyone's diet these days.