1. Do not bully others.
2. Do not oppress the weak.
3. Do not be a coward; help those in peril.
4. Do not engage in unlawful acts.
5. Do not use skill for immoral acts.
6. Do not be arrogant.
7. Do not sell/exhibit skill indiscriminately.
8. Do not join illicit gangs.
9. Do not waste time in idleness.
10. Do not be conceited and boastful.
11. Do not compete with the arrogant.
12. Do not argue with the ignorant.
13. Do not be influenced by worldly possessions.
14. Do not seek undeserved wealth.
15. Do not indulge in alcohol and lust.
16. Do not be in public or personal debt.
17. Do not obstruct public or personal efforts.
18. Do not hunger for power and position.
19. Do not be a traitor.
20. Do not neglect your training or waste your skill.
So when you start a martial art, ask if they have a code of conduct. Does it make sense? If there are no rules for conduct, consider that you may be putting yourself in danger.
And be happy.