Stay within Circle of competence to avoid big mistakes

"Warren and I have skills that could easily be taught to other people. One skill is knowing the edge of your own competency. It's not a competency if you don't know the edge of it. And Warren and I are better at tuning out the standard stupidities. We've left a lot of more talented and diligent people in the dust, just by working hard at eliminating standard error." - Charlie Munger in the Stanford Lawyer (Page 19)