We have one holiday behind us for the season. You do not have to let the holiday parties that are coming derail your healthy food goals.
Make sure that you eat something before you attend a party. "Saving up" all day by not eating is the worst strategy. It allows your metabolism to slow and by time you arrive at the party you are starving and unable to control the amount you eat.
Best strategy is still eat consistently throughout the day. Choose lighter items but still eat about every 3-4 hours and ideally consume a healthy snack before leaving. A great options is hummus and raw vegetables. They provide a healthy low calorie option with protein, fiber and water which can help you be satisfied and not be ravenous and overindulge at the party.