Throw yourself into as much experience as you can get. Always watch yourself. Try to understand your own motivations and other people’s motivations. Develop theories to explain human behavior and your own behavior and social movements. Study as much of every subject as you can. Constantly read. Always be curious.
You must also care. You must care about everyone and everything. Care about the universe as if it was yourself. In caring, you must look through everyone else’s eyes. You must be able to see things from everyone’s point of view and everything’s point of view if you hope to improve your insight and judgment.
I think caring is the most important thing. It isn’t about you any more. It’s about what’s best from all points of view. Or, if you want to do it from your point of view, acknowledge that and make it explicit to everyone.
Your job, in having good judgment, is to take the point of view that incorporates everyone and everyone’s interests. This must be done with love, or you can never get past yourself.
But to get there, you must live and you must have all kinds of experiences. In the process of living you will suffer. There will be pain, disappointment and heartbreak. You will run into brick walls (metaphorically) and be hurt badly. Don’t worry about making it happen. It will happen if you choose to live life fully, and to follow your bliss, as Joseph Campbell would put it.
Then you must be humble. This is probably hardest of all. For when you have good judgment, people will keep on complimenting you on it, and you must always resist feeling like it actually means anything. If you lose your humility, you will lose your insight.
Of course, this is what I believe, but it might be nonsense. I am probably deluded. But I try. And there is value in trying, even if you never meet the standard you set for yourself.