To expect someone to do better than their best is setting yourself up for disappointment and resentment. This includes if that person is yourself. Experience is the best asset to have in dealing with anything, and experience comes from mistakes. If you look at all the great inventors and scholars, they didn't get things right the first time. They just kept plugging away. That is what we need to do as well. Keep going and trying until we figure out what works for us.
Another big mistake is trying to get your self worth from what you think others think about you. This includes people you work for and with. About 5% of the people you meet will like you for whatever reason. About 5% will dislike you for whatever reason. 90% couldn't care less about you either way. If you come across someone that likes you, are you a wonderful person that day? If you come across someone that dislikes you, are you an evil person that day? See how crazy this can get?