Talk to your kids
You teach your kids how to cross the road safely. You discuss the dangers of talking to strangers. So why should it be any different online?
Tell them what to look out for, that they shouldn't talk to strangers and if they see anything they don't like they should tell you.
"Tell them not to share specific details about their physical location and be careful about accepting requests for online connections, such as become 'friends' with someone, or 'linking'" says Andrew.
You don't want to scare them away from using the computer, obviously, but a little bit of guidance can go a long way.