How can I improve my diet?

I want to eat healthier, and feel healthier. For breakfast I usually have Honey Bunches of Oat W/ Almonds with Vanilla Soy Milk. Lunch is usually a Turkey Sandwich, and Dinner is usually Lemon Baked Chicken and red potatoes with salad. I try to eat healthy, but I want to lose weight. What alterations can I make to my daily food intake to help that?