We are all biased. If you are confident to be a rational thinker, read this list of cognitive biases we all are prone to fall for. This is not an unusual behavior of our brain. In fact this is the only way our brain can work quickly and effectively.
But, at times, we do need to change gears and become more rational and better thinkers. The above list may help you recognize biases for your particular personality. You can then become consciously aware of a particular bias and make effort to not let it color your thinking.
There is another simple and better way to avoid these biases; Using deBono’s thinking tools. For example PMI (plus-minus-interesting) tool forces you to think up of negative aspects of an idea even if you are all for that idea. Similarly APC (alternatives-possibilities-choices) tool asks to take other possibilities into account even when you are feeling complacent with your choice.