It is always important to make sure your mechanical bull operators are properly trained and aware of the things that they should look out for in terms of rider safety. This video by Galaxy Multi Rides goes over the proper way for a participant to ride a mechanical bull & also things that the operator should look out for.
You should make sure that your riders are aware that there are certain things that they should not do such as: holding the bull horns or head of the bull, leaning forward on the bull and trying to stand up or do tricks on the bull. They also need to empty out their pockets, take off shoes & take off any hard items such as jewelry or eye wear. Also be sure that spectators are not allowed to lean up next to the device while they are watching someone ride the bull.
These safety tips should be applied to any type of bull or mechanical device.