A soft toothbrush.
  
It's important to brush at least twice a day using a soft toothbrush.  A soft toothbrush also facilitates much easier removal of plaque below the gumline, where periodontal disease starts.

Toothpaste with fluoride.
  
Use a toothpaste that contains fluoride. Fluoride hardens the outer enamel layer of the teeth. It might stop a cavity in its tracks and give you more resistance to future cavities.

The correct brushing angle.
  
Tilt the bristles of the brush along the gumline at a 45-degree angle and apply firm pressure so the bristles slide under the gumline. Vibrate the brush while you move it in short back and forth strokes and in small circular motions. Brush two or three teeth at a time, then move to the next teeth, allowing some overlap.