Multiple Jumpers
Many of the injuries seen from backyard trampolines come from people colliding or otherwise interfering with another jumper. This is why it is important to institute a "one jumper at a time" rule for the trampoline. While this may seem overly restrictive and take away much of the fun of jumping, it is nevertheless important for overall safety.
Somersaults
Experts recommend that somersaults and flips be banned from the backyard trampoline. Doing these sorts of maneuvers can easily result in injuries to the head and neck. Neck injuries can lead to paralysis and death. If acrobatic movements are to be performed, there should be adequate harnessing for the participants in order to cut down on the possibility of serious injury.
Open Space
Many injuries result from children jumping off the trampoline and accidentally hitting other structures or trees in the area. While the ground is not the best cushion for a fall, it is usually a safer alternative to hitting a playset or the stump of an old tree. For this reason, it is best to situate a backyard trampoline in a wide open space.
Enclosures
Trampoline enclosures such as netting can prevent jumpers from falling off the trampoline and injuring themselves on the ground. That said, the American Association of Orthopedic Surgeons warns that most trampoline accidents occur on the trampoline surface, meaning an enclosure could give families a false sense of security.
Supervision
The most important aspect of trampoline safety is to make sure any jumper--adult or child--has supervision in place before using the trampoline. A spotter or supervisor can be there to provide immediate care if an injury occurs and they can prevent accidents from happening by discouraging improper use.