The best way to brush the teeth is to tilt the toothbrush at an angle, so that it reaches the gumline. Use small circular movements to remove the plaque from the inner and outer surfaces of the teeth.
More specifically, the proper way to brush your teeth is the following:
Place the toothbrush angled on the gumline
Press firmly against the gums and use gentle strokes back and forth without moving the brush. Start with the outer surfaces of upper and lower teeth.
Then proceed in the same way with the inner surfaces.
To clean the front upper and lower teeth, tilt the toothbrush vertically.
In the end, brush the chewing surfaces of upper and lower teeth moving back and forth. Do not forget the back side of the last teeth.