There is two ways to conduct training, the first way is to tell the person, "Don't do this". As we all know, any person who is told not to do something, will do it as soon as the watchful eye is gone. Much like that famous quote, "When the cat is gone, the mouse is the boss". Simply instructing staff not to do something will require a keen eye from supervisors and management to maintain good behavior. It's the problem we see in our motor vehicle licensing, we are taught what we can and cannot do, however as we know, there is still death and carnage on the streets, that is because we don't train the drivers up on WHY they should drive a certain way.
This is how you should approach your training, first teach the attendees on what must be done, but spend a good time going through WHY it must be done. In other words, yes, we told you not to stick your finger in that electrical socket, but this is why, this is electricity, this is what it does to the human body, etc.
The person will walk away with their minds opened to the risks, meaning that they themselves will supervise their own work because their eyes would have been opened to the dangers and risks.