Keep your information private
Be careful who you trust online
Don't talk to someone you don't know. It could be a creeper.
Know your privacy settings
Make sure your settings are on private so people you don't know can't see what you post or be able to get information off your profile.
Know and Avoid Internet Scams and Schemes
If it seems to good to be true then it probably is! Don't click on pop-up ads either they are no good.