the worstest mistake you will do is giving up and not learning from your past mistakes because the greatest lesson in life is learning from your own mistakes.
NO, Actually, the greatest lesson is learning from other people's mistakes.
Think about this, it doesn't make any sense if you have to wait until you make a mistake before you learn, and what if you end up making a mistake you are not able to come out from?
So the best thing is, pay attention to other people's mistakes and learn from it, doing this will guide you to not end up making a serious mistake(s) yourself, as we all are bound to make mistakes along the line cus no one is above it, but the more we learn from other people's mistakes, the less mistakes we make ourselves.