ALWAYS remember to brush your teeth at least three times a day, and floss at least once!
Make sure to use toothpaste that contains fluoride, and ask your dentist if you need a fluoride rinse. This will help prevent cavities.
Avoid foods with a lot of sugar (sugar increases the amount of bacteria that grows in your mouth causing more plaque and possibly cavities) and avoid tobacco (this can stain your teeth, cause gum disease, and eventually lead to oral cancer).
Don't be afraid to brush your tongue! By brushing your tongue, you will remove food particles and reduce the amount of plaque causing bacteria. Tongue brushing also helps keep your breath fresh.
Be sure to schedule your routine checkup. It is recommended that you visit the dentist every six months.