You will need to do proper brushing technique and eat enough minerals so your diet will be balanced.
1. Brush and floss every night before you go to sleep. (Morning helps too of course, but night is far more important). Don't have anything other than water after you brush at night. And make sure your toothpaste has flouride in it.
2. Minimize acidic drinks (soda, juice, lemon water), or if you can't, at least drink them with a straw, and/or rinsing with water afterwards wouldn't hurt either.
3. Avoid snacking between meals. Remember, it's not just table sugar that causes cavities - any food with calories will do the same if it's stuck on your tooth.
4. Remove your wisdom teeth, unless your dentist tells you otherwise.
5. If you're a grinder, get a nightguard.