I explain what I've learned from creating and judging thousands of predictions on personal and real-world matters: the challenges of maintenance, the limitations of prediction markets, the interesting applications to my other essays, skepticism about pundits and unreflective persons' opinions, my own biases like optimism & planning fallacy, 3 very useful heuristics/approaches, and the costs of these activities in general.
Plus an extremely geeky parody of Fate/Stay Night.
I think I found political ones and ones I didn't research most helpful; anti-mind-killer and because most decisions must be unresearched, respectively. Personal ones and researched ones didn't seem to help much.
This essay exists as a large section of my page on predictions markets on
gwern.net: http://www.gwern.net/Prediction%20markets#1001-predictionbook-nights