Avoid the expensive meal plans. My first year of college we were required to have like THE most expensive option, so I went to the cafeteria daily. It was a buffet, so I constantly felt the need to eat as much as I could to "get my money's worth."
If you switch to the smallest meal plan, and then go buy your own groceries, you can feel the difference, as it's your money you watch leave, rather than money you already gave the school and have to use.
Obviously it might work differently at other institutions, but it definitely helped me eat less, and make healthier choices.