How to make good desicions in life, without the guidane of your parents/family?

I basically grew up without my parents. Only had one of them growin up althouh it wasnt really present either. Never gave me advice, or guidance like most good parents give their children. It never taught me to stand up for myself or not take shiz from anyone, or any of the things that caring-loving parents teach their children. I feel like because I didnt have any parental guidance, parents to back me up or support me that my desicions that I make now as an adult are affecting me. That somehow I'm vulnerable to certain attacks..How do you go in life living a good secure life when you dont have anyone to lean on? How to make good desicions when you dont know whats best, when you have no compass to lead you, per say..