Digital citizenship should be an ongoing and modeled practice by the teacher. But first, I would discuss the importance of appropriate, responsible behavior with excellent conduct when dealing with any technology. Remind the students of the kinds of decisions they must be aware of making 24/7. I might roleplay some situations where their peers may try to influence them inappropriately. And finally I would thoroughly discuss the digital law with them.Have the students make a list of actions that are illegal. It is a CRIME to hack, illegal download, create worms, send spam, etc.
Preach constantly how these criminals spend time in prison. Don't be afraid to report criminals to the local authorities.