it happends a lot

you can do eveything right and well. but what will be remembered is the only time you did sth wrong or not perfect. So one trick is to make yourself perfect by down play any possible mistakes and think of ways to overcome these issues. Also, make your boss on board with you is important. Thus, whatever mistakes, he/she will be part of it. So they will help you to cover it up. I learned this from a golden boy here. He is golden because he has all people to wipe his bottom for him.