IMHO by traveling. In my case I travelled a lot for work and was introduced to new places, people, and cultures (mostly micro cultures). Seeing how things are different from your local area gives perspective.

To a degree it’s just reflexive, a knee-jerk reaction to being told things without proper explanation. I struggled with that since I was very young. People told me what to do, what to think, how to feel, and I tried to obey but the stress of that obedience in the face of reason would always eventually end in meltdowns and by the time I was a teenager I was so worn down from that that I could barely function as a human being.

I was within a few years of twenty (pretty bad with dates) when the world showed me I had permission to think independently. There was a perceived familial obligation that I was too hurt to weather, an invitation to visit a relative that I found annoying. You’re told that you’re supposed to love your family, all of it, no matter how physically and emotionally detached they are from your life. But the act of trying to love a stranger that you can’t stand the company of and who cannot stand your company in turn, themselves only really trying out of this same sense of obligation that society pushes on them, there’s nothing in that but stress for all involved. And then you feel like a failure as a result, because you stressed them out and you’re supposed to be making them happy. It was a very small thing being asked of me and something I had always capable of weathering on previous occasions but this time I was too weak from the rest of life and, shamefully, I politely declined. I was kicking myself for the next hour, until somebody actually close to me caught me alone for a moment and praised that show of strength.

In my mind, she had always been stronger than me because she was better able to meet expectations. In that moment I learned that, in her mind, she was weak because she was unable to stand up for her own mental health needs and that I had just surpassed her by doing this. That realization changed my life. I let go of this obedience that my bones had always told me was wrong. Other people wanting something doesn’t mean I have to want it, other people feeling something doesn’t mean I have to feel it, other people doing something doesn’t mean I have to do it. Success at attempting all those things is exactly the same amount of suffering as failure, the very same action is both strong and weak. There’s no winning that game. Neither of us felt what we were supposed to feel and neither of us would be happy in the other’s shoes.

Society tells you that disobedience is arrogance, selfishness, but I’m a better person that I was before it. It made me more humble because I no longer felt that I was supposed to be right, now I want to be right and that means learning where I’m wrong. It made me more generous because I no longer felt that I was supposed to be good, now I want to be helpful because helping people feels good to do. It made me happier because I no longer felt that I was supposed to be happy, and now any instances of unhappiness don’t cause me the shame that negates future happiness. And it made me more tolerant because, fuck, I’m not about to start enforcing arbitrary standards on people when arbitrary standards caused me so much harm in the first place.

Now that there’s not an internal struggle against prescriptive conformity in the way, I’m freer than I ever was to do most of the same things everyone wanted me to do in the first place while also being able to set boundaries about those few things I know would be harmful to do.

It’s not at all frictionless to think for yourself, mind. People can be frustrated when you ask more justification of them than others do. If they’re doing what they’re told is right, saying what they’re told is right, believing what they’re told is right, it can feel threatening to ask them how any or all of that is right when, deep down, all they’re doing is playing their assigned role because they never had your epiphany. And the boundaries you set can also be at odds with the genuinely felt desires of those you care about because sometimes peoples’ desires are simply incompatible.

But that friction is nothing next to the cumulative psychic weight of total obedience. Mutual somewhat-grudging acceptance of each others’ limits is better than any one person’s permanent unhappiness.

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In terms of actionable advice: follow your logic, follow your feelings, follow observable reality. Recognize it as a red flag when people discourage you from that, and recognize the importance of hearing out people who are talking through their own logic and feelings and observations and scrutinizing each other.

By being autistic

Read books, it’s the poor people version of traveling to broaden your mind. Sometimes even more effective since some things cannot be experienced irl. They don’t need to be recent, the old classics are good. Think about the moral/ethics/philosophies you want to live your life on, then you can interpretate events according to those.

Learn, understand, challenge, repeat.

Learn as much as you can about all sorts of topics, even if you don’t have specific plans for those topics

Learn enough that you don’t just know the facts, but that you actually understand why things are the way they are. You should be able to predict things you haven’t yet learned if you understand the concepts. If you don’t understand something yet, keep learning.

Learn your fundamentals: language skills, math, logic, statistics, the science of research, history, politics, basic psychology, and the physics of whatever realm you’re operating in (meaning that in today’s day and age, you should learn about both real-world physics and about how information flows on the Internet).

A lot of people don’t know how to teach themselves, so it’s probably important to point out that learning to do so effectively is a big part of thinking for yourself. Learning how information is presented, as well as what’s often left unsaid, is important. Learn how to read graphs and charts and statistics. Improve your information literacy: Learn how to find credible sources, how to judge the credibility of a source, and what “credible” actually means. It doesn’t mean infallible.

As a general rule, don’t accept a fact until you have multiple credible confirmations of it. That might not be possible, but when information comes from untrustworthy sources, remember that. Learn the difference between something that you’ve learned and accepted and something that you’ve just heard on social media a few dozen times. This is easier when you have an understanding of what you’re learning. True things fit in better with other true things.

Don’t assume things are false just because the source isn’t credible, either. Just do extra research to verify. Do your own experiments to confirm, if possible.

Sometimes you’ll realize something you’ve accepted might be wrong, possibly because it conflicts with something else that you learned. When facts don’t add up, challenge them. You’re not infallible. Replacing a fact you accepted long ago isn’t a failure; it’s a victory. Many people are incapable of doing so.

Learn to distinguish between facts, inferences, theories, and opinions. (Note that established, accepted scientific theories often fall into the “fact” category.) Facts are verifiable. Inferences are based on facts; they’re evidence-based conclusions that can help to build theories. Theories are explanations, and they can be disproven but haven’t been proven (else they would be facts). Information presented as facts can be false. Theories and inferences can be poorly formed, even if the facts are sound (and especially when they are not). “Opinion” is a word people use to defend flawed theories. If the opinion isn’t a preference, there’s a good chance it isn’t an opinion at all and is just intentional misinformation. “You can’t argue with my opinion” isn’t applicable when the “opinion” is provably false - then it’s just a failed fact, inference, or theory. And even when it is an opinion, it can still be criticized.

Learn about logical fallacies. Even if you don’t call out the person using them, try to notice them in the wild, both by people you agree with and people you disagree with. But especially by people you agree with. Learn how to notice other ways people are misled.