The first trick relates directly to the problem we addressed in the introduction. How much you serve on your own plate will determine how much you try to eat. Serve enough food so that you know you will go back for seconds, and then eat slowly. Odds are that by the time you are finished, you will realize you weren't as hungry as you had thought. If you serve small amounts and eat them slowly, then you will allow you stomach time to adjust to the amount you have just eaten, and signal your brain that you don't need more. This is a great way to control how much you end up eating each meal.
Second, you should buy small tupperware containers. If you have massive tubs of tupperware, then the odds are that you will fill them with food and eat it all. If however you have small tupperwares, then you will put smaller amounts in them, and that will ensure that you don't stuff your face when it comes time to packing lunches and eating out, whether in a picnic at the park or at your office.
Finally, try to cook less food. If you make an entire roasted chicken for yourself, then it is possible that you might try to eat it all by yourself. Instead, cook smaller portions in your pots and pans, small enough that you will eat the correct amount and not be tempted by steaming heaps of food that are left over.