1: Stop expecting from others. Expectations only lead to disappointments.
2: Never blame anybody for your mistakes and failures.
3: Never make a promise when you are emotional.
4: Never say or do something that is going to affect anyone negatively.
5: Don't believe in things that you haven't seen by yourself.
6: Never feel ashamed to admit your mistake.
7: Never take your all friends home. Be selective. Don't trust everyone blindly.
8: Never share your personal life with everyone.
9: Never underestimate yourself. You can definitely do if you want to do.
10: Never compare your life or your people with others. The fingers on the same hand are not same so we cannot expect anyone be same.
11: Never get addicted to anything so seriously. It can be a thing or a person or a habit.
12: Never tell any secrets in front of the kid. They are catchy and can bring you an embarrassment in the public.
Source: https://humanmindreaders.quora.com/What-are-the-12-things-we-should-never-do