Once one groks these three principles, what should one do next?
Succeed.
No, that is exactly wrong. The whole problem is that no course of action guarantees success. The world is throwing curveballs.
My own solution is to shift my terminal values to the meta level. Instead of demanding success of myself (and then feeling bad if success turns out to be unattainable) I reward myself with a gold star if I judge that I have done my best. I live my life so as to have no regrets.
The difficulty (you might call it a trap) in this approach is in the need to retain a brutal honesty. It may be very tempting to respond to failures by giving yourself the star anyways, with the excuse "How could I have known?". How could I have known that wouldn't work? How could I have known that is not what they wanted? How could I have known that my 'friend' was a con artist? There may well have been a way you could have known - clues that you missed.
It can be tricky finding the middle road of learning from your mistakes, without falling into the error of denying mistakes or obsessing over them.
I live my life so as to have no regrets.
Maybe you will like this one:
No Regrets, or: Edith Piaf Revamps Decision Theory - Frank Arntzenius
Recently, I've been ratcheting up my probability estimate of some of Less Wrong's core doctrines (shut up and multiply, beliefs require evidence, brains are not a reliable guide as to whether brains are malfunctioning, the Universe has no fail-safe mechanisms) from "Hmm, this is an intriguing idea" to somewhere in the neighborhood of "This is most likely correct."
This leaves me confused and concerned and afraid. There are two things in particular that are bothering me. On the one hand, I feel obligated to try much harder to identify my real goals and then to do what it takes to actually achieve them -- I have much less faith that just being a nice, thoughtful, hard-working person will result in me having a pleasant life, let alone in me fulfilling anything like my full potential to help others and/or produce great art. On the other hand, I feel a deep sense of pessimism -- I have much less faith that even making an intense, rational effort to succeed will make much of a difference. Rationality has stripped me of some of my traditional sources of confidence that everything will work out OK, but it hasn't provided any new ones -- there is no formula that I can recite to myself to say "Well, as long as I do this, then everything will be fine." Most likely, it won't be fine; but it isn't hopeless, either; possibly there's something I can do to help, and if so I really want to find it. This is frustrating.
This isn't to say that I want to back away from rationalism -- it's not as if pretending to be dumb will help. To whatever extent I become more rational and thus more successful, that's better than nothing. The concern is that it may not ever be better enough for me to register a sense of approval or contentedness. Civilization might collapse; I might get hit by a bus; or I might just claw through some of my biases but not others, make poor choices, and fail to accomplish much of anything.
Has anyone else had experience with a similar type of fear? Does anyone have suggestions as to an appropriate response?