Learn to anticipate your hunger. Allowing yourself to become overly hungry is what causes most people to make poor food choices. If necessary, set a specific time for a light snack. You'll feel more in control. If you have an urge to snack and you know you're really not hungry, brush your teeth instead.
Most people hate to eat after they've brushed their teeth.
Pay attention to your body's hunger signals. From time to time, you may have to eat when you're really not hungry. Take a few seconds to check your hunger level and choose what and how much to eat accordingly. So often we eat on the run and never really enjoy our food. Your brain needs 20 minutes to register that you're full, so eat at a moderate pace and pause between bites and courses.