Ok I need some help on food choices. My MIL's birthday is Sunday and my SIL called to tell me that we are going to Golden Corral. Great a buffet

. Well, I am worried about going over on my calories, not because I feel that I will binge but because I have no way to weigh and measure what I eat or what my best choices will be. Any advise?
Thanks!
PS. This is just one of the birthday parties I have to attend next week, all will be at restaurants.