Know that you don’t know.
The vast majority of us are ignorant about pretty much everything. A tiny minority of us are somewhat knowledgeable in one or two subjects.
But all of us have the power to be able to recognize our own ignorance, and that recognition, all by itself, will make us wiser than a million memorized facts and figures ever could.
Even having a PhD is no guarantee that a person knows much of anything; if anything, it will only provide more temptation for the person to believe they know more than they really do. Still, don’t think that fact puts us above them in the ability to think or understand. If even the person with a doctorate is mostly ignorant, how much more are the rest of us?
There is nothing that’s as endearing as someone who admits to ignorance, and withholds judgement on the basis of that ignorance, and is open to having it remedied if a competent teacher should appear.
The good life is knowing one’s own ignorance, making peace with it and not being defensive about it, seeking continually and patiently to remedy it, and learning from others when they can teach us. It’s surprisingly easy to see when others are really knowledgeable once we finally encounter it; almost all others will believe themselves knowledgeable, and will be able to give reasons for their beliefs, but it is the rare person whose beliefs are actually proportionate to their evidence who can teach us, or at least accompany us in a way that is help rather than hindrance.