Don't give away your information. Don't have a gamer tag that says your name. Don't give away passwords even for accounts you don't use.
If you decide to download something you're not sure of use a virus scanner that will tell you if it is safe or not. If you get suspicious emails with links don't open them. Be careful of malware and spyware.
Don't be a jerk to other people online it's not nice. Don't be calling people names online. Be nice online it is lust something you need to do.
If someone is bullying you tell and adult about it. If the bully doesn't stop keep the messages or screenshots and report them to a cop. Don't be a bystander if you see it online tell them "not cool" Cyber bullying is not nice
Be careful what you post online any body can see it. Think before you post if it might be offensive don't post is. just be nice online and be careful of what you say.