Track your foods the day before you plan on eating them. That way, you're not tempted to eat foods that aren't on the tracker. Part of it is being too lazy to change it once you've put it in.
However, make sure you track treats for yourself on special days or weekends so you don't feel deprived. I usually have one "sweet" per day (such as pudding or a popsicle, etc), and I track one alcoholic drink (or two) on an evening out on the weekend.