1. Accept Being Wrong
In order to effectively navigate life the human mind is designed to constantly take shortcuts. The brain uses tiny bits of data, a few pieces of a given puzzle, and then compensates for the missing pieces with its “best guess.” The result is a tendency for humans to be wrong… a lot!
Optical illusions are possible, because the brain automatically fills in the spots where visual information is missing by using patterns and expectations from past experience.  In other words, what you think you see may not be what is actually out there!
If you blindfold someone, hold and apple under her nose, and have her bite a piece of raw potato, she will be fooled into thinking she bit a piece of apple. The brain takes a small amount of information, smell and texture, and makes a judgment, "I must have bitten an apple." 
This also happens when we meet new people. We know very little about the new acquaintance, but quickly judge his character, "He seems dishonest." When we get to know him, reality fills in the blanks and we find that he is extremely trustworthy.
There is a direct correlation between how easily you overcome your own biases (traps that lead to being wrong) and IQ level. The smarter you are, the easier it is to overcome your biases (accepting that you are wrong).
Critical thinkers examine issues from many different angles, so the world operates more in shades of gray, than of black and white. Being wrong feels exactly like being right... until someone PROVES you are wrong.
2. Beware of Cognitive Traps
There are many ways we fool ourselves into believing in things that are absolutely not true. Many cognitive traps are just side effects of how humans are wired. Because they tend to crop up in all people, these traps require diligent work on our part to overcome.
Confirmation Bias is a trap wherein you believe that you have determined a "truth" based on rational thinking, but in actuality, you have simply dismissed all evidence disputing your pre-existing belief and accepted all information confirming said belief.
Example 1: You don't believe in global warming, so you disregard the 97% of climatologists who support global warming and accept the 3% who dispute this phenomenon. You may reason that there is a conspiracy (a catch-all explanation that is very rarely accurate).
Example 2: You think immunizations cause autism, so you disregard the avalanche of research supporting the efficacy of immunization, but believe the one flawed study linking vaccines to autism. You reason that there is a conspiracy.
Hindsight Bias is a trap based on the idea that people should be able to predict the future. Have you ever been stumped by a riddle and after hearing the solution you thought, “Wow, that was so obvious. I should have easily figured it out”? In truth, since you do not have the ability to predict the future, the solution to the riddle was certainly NOT obvious.
Empathy Bias is similar to hindsight bias, but is projected on others rather than self. If a friend is in a bad relationship, it may seem obvious to you that your friend should end the relationship. You may consider her reluctance to do so, as “stupid.” However, when you, yourself have been in bad relationships, this “obvious” solution of breaking it off was not so clear. Why was your friend’s relationship problem so easy for you to solve, and your relationship problem so difficult? When you have real empathy, you make a sincere attempt to understand things from the other person’s perspective.[9 You try to "stand in their shoes." This is especially difficult when you perceive that the other person is different from you (eg different nationality, different race, different religion, different sexual orientation, etc.).
3. Trust Evidence Over Emotion
In some ways, humans are not very different from lower animal species. We almost always operate from “gut feelings,” or emotions. After making an emotional judgment, we create rationalizations (poorly reasoned arguments) to justify why these feelings, and resulting beliefs, are accurate.
To whatever degree possible, critical thinkers start from a neutral position and do not invest their respective egos in pre-existing beliefs. Good critical thinkers allow the evidence to determine the accuracy of a piece of information. Ego, “because it is my thought it must be true,” is by far the biggest obstacle to rational thinking.
Overcoming the ego obstacle requires that truth, as determined by objective evidence, always take precedence over our instinctual need to be right. All it takes is a lifetime of practice.
4. Learn to Metacognate
Metacognition means, “thinking about your own thought processes.” Most of us have the tendency to allow our emotion thoughts to lead us around by the nose. Dumb animals operate in this manner. This tendency to attach our egos to the accuracy of our gut feelings is a root cause for ignorance.
If our failsafe is to assume that our thought processes are always accurate, we remain trapped in a bubble of ignorance.
Fortunately, if we consistently apply humble skepticism, logic, and metacognition, humans can escape the intellectual prison created by blind trust gut feelings.