Ten Rules of Economic Thinking

I was preparing myself for an interview and started thinking about what are some economic rules (objectives) that the students should leave the class with. I thought of "there is no free lunch", "people try to maximize their utility and minimize their costs", and my ADHD took over.
My eyes went to a book on my bookshelf called "Sex Drugs & Economics" by Diane Coyle.
She has listed the following:

1. Everything has a cost
2. Things always change
3. There are no time bombs
4. People do what they want
5. Prices make the best incentives
6. Supply and Demand works
7. There is no easy profit
8. Always look up the evidence
9. Where common sense and economics conflict, common sense is wrong
10. Economics is about happiness