Make sure the helmet fits snugly and does not obstruct your field of vision.
Always wear the helmet with the chin strap firmly buckled. Make sure the chin strap fits securely and that the buckle stays fastened to provide impact protection. No combination of twisting or pulling should remove the helmet from the head or loosen the buckle on the strap.
Wear the helmet flat atop your head. Do not wear the helmet tilted back at an angle.
Do not use a helmet after it has been involved in an accident. Damage to the helmet may not be visible to an untrained eye. Even very small cracks in the helmet may greatly reduce a helmet's effectiveness in preventing injury. Either destroy the helmet and get a new one or have it inspected by the manufacturer. The manufacturer will tell you if the helmet needs to be replaced.