Tip #1: Make Your Usernames Safe
Don't let your usernames related to you. For example don't give out your gender, age, hobbies, or address.
Don't send or respond to mean messages. If you are cyber bullied the talk to your parents about it.
People aren't always who they say they are. They could try to meet in real life. If they do say no or ask your parents first.
Some online shopping sites are safe. Others are fake and will try to get your credit card and buy things.
Some pop-ups like the one above say that you won something but really they are trying to trick you. If something pops up the best thing to do is to say no or exit out.