Eliminate any distractions. Turn off the radio. Switch off the television. When you sit down at the table, eating should be your main focus. When other things are going on around you, you're less likely to concentrate on what you're eating and how much you're eating. Besides this gives you the chance to actually savor your food and taste it.
Don't just "wolf" it down. This can cause you to overindulge. By focusing on the task at hand, you'll be more likely to stick to the proper portion sizes. Take your time and make sure to drink plenty of water before during and after a meal.