Start a journal. Write down where you were, what you were feeling and how you responded every time you overeat. You may find a pattern to your overeating. If a place sets you off, you might be able to avoid it. If a feeling sets you off, you will have to learn a different way to manage it. Food and emotions are usually related.
Eat at regular times. The biggest mistake is skipping meals and having no regular time to eat. When you skip meals, you set yourself up to overeat. When you eat on the run, you tend to grab fast food or food low in nutrition but high in empty calories.