What I always try to do during the holidays is to eat slowly and in good size portions.  This means that if there are 10 different dishes on the table, it won't take very much of any particular dish to fill me up in the end.  So, take just a small bit of everything, try it, and then if there's something that you really loved, take a little bit more.  But, don't go crazy with stuffing yourself.  It's not necessary and this is the main reason why so many gain weight during the holidays.  Also, try to stay in a routine of getting some exercise, even if it's speed-walking every day for 20 min.  If you keep this up, you'll stay around the same weight for the duration of the holidays.  Good luck and happy holidays!