I would start by taking the answers given here with a hefty portion of salt. It is fairly shameful to answer this question with authority, so largely you are s

I would start by taking the answers given here with a hefty portion of salt. It is fairly shameful to answer this question with authority, so largely you are selecting for shamelessness among the answerers. I am revealing my own shamelessness then, now, by answering you. To start with, the main thing that is required for my process is an emotional investment. This isn't dispassionate analysis. Truly critical thought requires, in my experience, a strong fear of being wrong. I do not believe there is a shortcut to this. Fear is a powerful motivator, and if you are not afraid of being wrong, then why do you care at all? The fear drives an internal adversary that tries to find flaws in all encountered beliefs. Preempting the arguments that could be used against you if you were to hold them. So afraid are you then of being wrong, that you will change your mind. You will do this even if it means you will disagree with people you don't want to disagree with. You will fear being wrong more than not agreeing with them. This fear should be relentless, but it does not have to be unpleasant, and by submitting to it completely, you can gain true confidence in your beliefs. The adversarial process does not always converge upon the truth, but it does at least converge on something that is hard to refute. I have one more piece of advice, but I'm not sure how applicable it is to everyone. There is no such thing as true or false for beliefs. Or rather, you should not act as if there is. Whether a belief is true or false is one of the less usefull things about it. Instead, you should consider beliefs as resting on top of each other, in a sort of jenga tower. Since you have committed to potentially changing your mind about anything, it is far more important to keep track of why you believe things, than that you believe them. If you then do change your mind, you can be less wrong in a lot of other ways for free just by letting the jenga tower above it fall down.