One of the best rule of thumb things that you can do to serve the right portion sizes is to use your hands. Have a look at your hands. Serve a meal where the protein size can fit in the palm of your hand and the vegetable portion can fit into the palm of the other hand. These two portions will be enough to give you a satisfying meal.
One of the best ways to ensure that you do not blow out your portions is to eat regular meals and snacks. If you are famished before a meal then you are more likely to eat bigger portions. Eating meals and snacks at the same time each day helps your body to program the hunger hormone. It programs your body to tell you that it is time to eat. When you eat small regular meals through the day you are less likely to become over hungry and overeat.