critical thinking. Question everything (even in your head). Does this make sense, does this have valid data? Importantly: Is this actually relevant to me? If not skip it.

One of the clearest thinkers I had the privilege of knowing was Dr. Eli Goldratt author of Theory of Constraints.

Fortunately for us he defined as his life's mission to teach the world to think clearly.

So I suggest you start with three of his books: The Goal, Is not luck and The Choice. After trat read "The thinking Processes".

Apart from the theory of Constraints literature you can study system dynamics. And if you like programming then "Introduction to NetLogo" is great at both.

If you don't like programming then Zenge's the "Fifth Discipline" is a great intro to system dynamics.

I think of myself as having average intelligence. When I worked hard I could get As when I slack off I can sneak by, when I do average work I get average results. This makes me perfect to answer because nothing comes easy to me but nothing is out of reach if I apply myself. I do alright because I’ve put in the effort and here’s how.

Evidence based thinking: (what is the evidence backing this conclusion and how trustworthy is it?) without this everything you believe is no better than fantasy.

Room to be wrong: what if my prior assumption is incorrect? Can I admit that and get better? Without this you can never improve. (Also if you can’t ever admit you’re wrong that’s essentially the definition of being an asshole)

Avoiding perspective /assumption lock: there are classic thinking problems like the one that spawned the term thinking outside the box (look it up and answer for your self how this might be assumption lock). The apocryphal Charley Munger effort to armor planes better in World War Two (it was actually someone else’s work and far less cut and dried but interesting), the actual Charley Munger effort to save the lives of pilots by inverting and solving (how do I save the most pilots? Invert that and it’s obvious, now invert again and you have a solution)

Then practice. Seek out thinking problems, read about solutions to thinking problems and see if you can find similarities in solutions, thinking traps to avoid.

Try out chess and see if it gets you thinking ahead or about what other people might do. (Most people in prison can’t draw a causal relationship between their actions and their situation, chess taught me to not be like that)

Read the classic book on systems thinking and see if it resonates with you

Talk to people who challenge you intellectually (people who can successfully convince you of something you didn’t think before). Socrates says the loser of the argument is the one who benefits most. Because he leaves with new ideas. The winner only gains satisfaction and that is worth far less than knowledge. Immediately after this step, return to step one and check evidence closely, because making a convincing argument is not always correlated with correctness. A convincing argument on faulty evidence is worse than useless. (Look up what Socrates says about sophistry)

Keep in mind that there are many types of intelligence. Emotional intelligence, financial savvy, street smarts. If you’re not trying at all in any of those areas you’re leaving money on the table. My buddy has low school smarts, high financial intelligence. His financial management is 100x better than his rich friends. He’s not “smart” he just tries harder, follows best practices, vets advice carefully and does the work.

Go do the work Lay out some areas you want to get better. Look up best practices, vet them, practice them.

You’re already on the right track. (Excuse me I gotta go do something that guy told me to do but I never got around to)

Try to dig what a thing actually is, not what people say it is. Write down your current understanding with a date, so you can see years later how wrong or right you were. True learning is ugly route. Refine your own definition/understanding to be real-world bullet-proof. You need to be less-wrong over time. Use your bullet-proof learnings to build something, and don't let all the faux renduntant new ideas or manipulative generated comments destroy it.

Try to explode different things, so you can see clear boundaries of each separate thing and to minimize redundancy.

Try to map the depencency graph of a thing. Every higher level thing is a make file / spreadsheet cell DAG.