Brushing and flossing are important but the dietary stuff (avoiding sugars (especially stickier ones) and sticky carbohydrates (crackers/chips/pretzels) and acidic things (sucking on lemons all day, sour patch kids) is also equally important. Here's a good guide for those with kids who struggle with decay despite decent to good oral hygiene. http://www.thedentistdad.com/snackguide/