There are actually over a hundred. These are my main guidelines.
a. Cats are good. Cats are safe. If in doubt, go to Cats.
b. Don’t go looking for anything that you don’t want to see. If a friend says “Hey, google this”, don’t. Go to Cats.
c. If you find something that you don’t like, close it, back out of it, turn it off. Go to Cats.
This may seem humorous, but the point is to remember that you control how you interact with the internet. If there is any doubt, there is no doubt, go to Cats.