Switch your fork to your less dominate hand. Not only is it more difficult to pick up the food and cut the food but it forces you to slow down your consumption.
SWITCH ALL YOUR DINNER PLATES TO SALAD PLATES! This tip is a great way to "fill" up your plate and eat the proper portion size. Dinner plates are extremely larger and we tend to feel unsatisfied when the plate is not filled. Using salad plates tricks your eye into thinking you are eating more.
This is a great tip if you love sweets. Eat all your desserts, cake, ice cream, pie etc in a nice glass (champagne flute, martini glass or white wine glass). Your serving size is automatically smaller but you feel like you are indulging because of the presentation. This is also a great idea for your next dinner party.