You should stay away from two major types of food and drinks: Sugary and Acidic.
Acidic drinks: research has shown that any drink with a pH < 4.0 can cause dental damage even in the absence of bacteria. Common drinks with a pH less thank 4.0 includes lemon juice, Coca-Cola, Gatorade, Kool-aid and more.
Sugary food: candies and sweets with caramelized sugar are very hard clean around brackets as they stick hard. This includes Twix, Caramel, Milkiway, and more