What's something dog owners know that everyone should know?

Here are just some rules I usually teach my nieces.

1. Rough housing isn't allowed.
2. If you want to approach my dog, get him to smell you first.
3. Try not to pet the head immediately. It can be perceived as an act of dominance. Highly reactive dogs might even resort to biting.
4. Don't go excitedly saying how cute he/she is because it's annoying to me and can be intimidating to her.