It begins with the way you treat yourself, continues with how you treat other human beings, and ends with the actions you engage in your daily lives.

Along with other things to follow everyone may consider...thou shalt not have any strange gods before Me. Thou shalt not kill. Thou shalt not commit adultery. Thou shalt not steal. Thou shalt not bear false witness against thy neighbor. Thou shalt not covet thy neighbor’s wife. Thou shalt not covet thy neighbor’s goods... isn’t it a good start to be enlightened?
I do agree with you especially about “doubt”. People shouldn’t doubt themselves. But there is always this subconsciousness. I don’t think you can avoid it at some point, but it’s only up to you if you let it take you down, if you let it beat you. There was this “person” in my childhood, who said “you are a looser, you are a quitter”. But because I knew it wasn’t true, because I knew it was evil trying to take me down, it didn’t make me doubts about myself at all.