OK, I am a person of habits. And, honestly, we all have one or more habits that we learned the hard way in our lives.
As for myself, I have lived long enough to have already made a lot (hopefully ALL) of my major “Common Life Mistakes”.
There are so many simple ones that we learn as we grow older, like;
I’ll not be putting my hand in a fire (It IS going to hurt, fool!),
I will not walk down a dark street, in a strange neighborhood, late at night (this one is a movie thing, I guess I have watched too many of them that have flagged this as being inherently dangerous.).