You said it yourself. More vegetables. That's where the vitamins, minerals and antioxidants are. Mark says to eat unlimited produce if I remember right. I eat about 1.5 to 2 lbs of non-starchy vegetables a day. I make sure to eat from leafy, cruciferous and colored each day. They don't add many calories but they do add a lot of nutrition.
Wow, I never thought I'd end up sounding like my Mother.