Here are some tips from PSMommies on how you can make decent choices and enjoy your evening out.
When ordering at a restaurant, try to avoid fried food and foods covered in heavy sauces. If you can, order the fish or salad (ask for dressing on the side to avoid eating too much), or get broiled chicken or lean meat. If you're absolutely craving a burger, get a plain one without the works (no bacon or cheese) and choose the salad or a broth-based soup instead of fries.
If you're choosing an ethnic type of restaurant, Japanese food tends to be very light and non-oily, while Chinese offers most dishes pan fried and cooked with oils (although the steamed veggies and shrimp are cooked in a light conrstarch based sauce that is very diet-friendly. Look for similar dishes when choosing.). Mexican is often loaded with cheese and oils, but you can try to get bean and chicken based dishes without all the extras for a lighter fare. With all restaurants, you will have to make a concerted effort to determine what is in a recipe. Don't be afraid to ask the waiter.
Pizza, in and of itself, is not a bad food. When you load it with greasy pepperoni and sausage, extra cheese and stuff the crust with even more cheese --that's when it earns a bad name. Load a thin crust pizza with veggies and you've got a decent meal. Just don't go back for that third or fourth (or more) piece. If you're going to have pizza, just plan for it the rest of the day and eat lightly so as to have enough calories or points left to enjoy it.
Many restaurants serve more than a normal serving size. Try to limit yourself to a regular portion and take the remainder home for lunch the next day. If you find it hard to stop once you start, cut the extra off and move it to one side of the plate, or ask the server for a "to go" box when they bring the food and immediately place the extra portion inside.