Always eat from a plate. First, put the chips or other finger food from the communal bowl or bag onto a plate. This way you have a better sense of how much you have eaten and won't mindlessly munch chips. Once you put your snack on a plate, put the bag away. Don't leave the bag sitting on the counter for a quick refill. If you are determined to get more, make yourself get up, go to the pantry, refill your plate and return the bag to its cabinet.