You should follow a low-fat, reduced calorie diet with a variety of foods from the food groups. Exercise goes hand in hand with this. It's so easy to nibble and lose track. But I don't want to be a 'party pooper' either. Remember, go through the line only once.
Moderation is the key.
First, you have to look at your goal for the holiday eating. A good goal is for your weight to break even during the holidays. Look at your week, and plan your eating for special occasions. Also, do not neglect exercise. People tend to forget it during the holidays.