Back in 2004, when I was in secondary school, my P.E. teacher said something during a basketball lesson:
Practice doesn't make perfect, practice makes permanent
We all looked puzzled when he said it, then he explained:
If you practice doing something wrong, it gets ingrained into you and it's difficult to change that.
It's very true, and the quote has stuck with me ever since. It can be applied to almost everything you do in life, from programming to cooking to sports. This is why it's important to do two things:
Nobody, no matter what their position, experience or background, should be afraid to ask for help. Asking for help means that you understand your limitations and that others may be better at something than you, even if it's just one small thing. Everyone has their strengths and weaknesses.
Nobody should be afraid of giving help either. You gain nothing by keeping your experience and knowledge secret. Everyone had to learn from somewhere and almost everyone has learnt from others. Keeping your knowledge and experience to yourself simply means that you make it harder for others to join you in doing whatever you have the knowledge and experience of.
Adam Savage (one of the Mythbusters) talked about asking and sharing in his 10 Commandments for makers address at the Bay Area Maker Faire.
Everyone gains from you asking for feedback. It allows whoever is giving the feedback the opportunity to express their opinion and allows you to see what others think. This also opens a window for discussion, meaning that you can potentially find out things you didn't know before which in turn could help you improve.
Never simply discard someone's feedback without a conversation, talking about someone's feedback can help you see it from their perspective and could completely change how you look at it. If after a conversation you don't agree with them, then fine, but at least you took the opportunity to explore.