(Extracted from Kahneman, Thinking Fast and Slow):
Adopt a scientific attitude: Avoid judgments without knowing enough facts. Disprove, rather than confirm. (confirmation bias)
Be careful about your decision-making: consider anchoring, framing, substitution, and loss.
Learn more about statistics, and question opinions. What other people think or do is not a good guideline. Even if many people believe something to be true, it may be false.
Seek outside perspective on your live. Teachers, friends, therapists, managers, coworkers, parents.
Don't over-estimate authority. Question experts.
Operate by searching, rather than by assuming. Ask many questions.
Use the associative machine and priming effects to your advantage. This is the source of your creativity.
Utilize cognitive ease, avoid jumping to conclusions, be critical to the Halo effect.
Correct overconfidence. Be mindful that bad news get overestimated as well.
Endowment Effect: The (emotional) response to a loss is stronger than the response to a corresponding gain. Therefore, build loss experientially into your system. (Everything that rises must come down.)
Remember: Happiness is a memory, not an experience. "Odd as it may seem, I am my remembering self, and the experiencing self, who does my living, is like a stranger to me."
Study yourself, and work hard on self-improvement.