No gum, caramel, taffy, fruit roll ups, gummy bears, or so on. These stick to the braces and your teeth, and can cause cavities and break your braces. Do not chew ice, hard candy, pizza crust, popcorn, hard breads, bagels, granola bars, or peanuts. Never eat meat from a bone or open nuts with your teeth. Do not eat pretzels, beef jerky, or Doritos either. Also, when you eat hard foods like carrots and applies, slice them up before you eat them.
With braces on, you should brush your teeth at least 4 times a day (after breakfast, lunch, dinner, and before bed). Try to brush at school. If you cannot brush at school, at least make sure you rinse your mouth after lunch. You can use floss threaders, super floos, or a Proxabrush to help you floss under the wires.
The mouth is very sensitive so you can expect an adjustment period and some discomfort due to the introduction of orthodontic appliances. Non-prescription pain medication can be used during this adjustment period. You can also place wax on the metal brace section that is bothering you.