Look at positions that oppose your and try to see the merits of them put yourself in the shoes of a diverging point and on those shoes you'll probably find an issue with your own point, even if the shoes you wore to do so were wrong as sin, changing the perspective helps.

Other than that I think that the constant balancing of conviction on your position to the point of acting on it but humility to recognize that it could be wrong, and strength to correct course when you realize it's wrong. This last part, to internalize that you might change part of your beliefs and if so pivot to the new one with the same conviction as before, this point is important, because once you accept it as a possibility and realize that its not reason for shame, you become less prone to holding on to dear life on an outdated or incomplete view. Those are all hard things to do but I believe it's through there.