Perhaps a good place to start would be the literature on life satisfaction and happiness. Statistically speaking, what changes in life that can be made voluntarily lead to the greatest increase in life satisfaction at the least cost in effort/money/trouble?
As rationalists, we should be able to consistently and accurately make predictions that enable us to act effectively.
As humans, we don't. At least not perfectly.
We need to improve. Many of us have, or at least believe we have. However, it's a notably hacked improvement. PredictionBook is an excellent source of feedback on how well we're doing, but there's more detailed information that isn't easily available that I think could be incredibly useful. Questions I would like to see answered are: