1. First tip is definitely not to get too tempted, remember you are only eating more than your average intake because you have paid more than average for a meal, but the good part is there is a lot of variety so make this a quality rather than a quantity experience
2. Second tip would be to start with natural sugars found in buffet fruits before you move on to appetizers and main course, this way you get some healthy nutrients absorbed by your stomach first which will also slowdown your appetite before you get some fats and carbs from your main course.
3. Try to replace your dessert with a hot beverage followed by a little walk home.
4. Be happy and satisfied, you paid more and got healthier, all make sense.