The only way is to learn for yourself. I see plenty of people, parents, whatever trying to teach their kids or proteges if you will from their own experience. It's very hard to learn from someone else's mistakes - you gotta make your own.
And stop doubting yourself so much, man. Why do you need a mentor or advice? You should give yourself advice because in the end, if you make a mistake, you're the one who's gonna have to live with that. Not your mentor, not your friend, no one.
There is no such thing as the right advice. There is only what works for me. And what works for me might not work for you, although I may have given you the advice with your best interest at heart.
I get this but also can't agree. As humanity we progressed so much because we could learn from the mistakes of our peers and get the lessons they worked hard for so we don't have. Discounting a whole millenia of human experience as well as the fact that some people ( teachers) spend years learning how to be good at something so you can learn faster ( also mentors/coaching/etc). is not my idea of wisdom. Maybe real wisdom is knowing when you really need help and how to seek it...