Brushing and flossing may not be enough. The ADA now recommends using an antimicrobial mouthwash to reduce plaque and prevent gingivitis.
Replace your toothbrush every 3 or 4 months, or sooner if the bristles are frayed. A worn toothbrush won't do a good job of cleaning your teeth.
For healthy teeth and gums, eat a balanced diet and limit between-meal snacks. Go easy on sugary treats!