Watch food labels. Keep all food in the kitchen or pantry, not in any other places. Never skip meals, you must have some kind of nourishment regularly or your body's starvation defenses will kick in, lower your metabolism, and store fat. Use nutritional meal replacements instead of skipping or eating very low calorie meals. The calories still add up and must be burned off regardless of what kind of food you eat.
Balance is key.
Give away or throw away leftover food. Don't put extra food in bowls and kettles on the kitchen table. Keep it in the kitchen or put it away. Write it down. But the overall trend is important.