Improve the Art of Good Guesswork : Mauboussin

From the man teaching the course at Columbia that the mighty Benjamin Grossbaum himself taught (first) back in the day :

1. Understand where you are on the luck-skill continuum. The tighter the spread of skill, the more luck will play a role. Baseball and ice-hockey (most) are very luck dependent and basketball (most) and soccer are more skill dependent. Skill dependent => predictable. We are wired to assign causes to events. We are not good as distinguishing between luck and skill.
2. Assess sample size, significance and swans (i.e., black). "Belief in the law of small numbers" - Tversky/Kahneman. In baseball, strike-out rate is a better predictor of skill than batting average. Beware of economic/statistical significance. Remember the experiment where looking at sales would have told them advertising hurt sales? You need to look at the right thing - did market share improve? Also, useful results aren't always dramatic enough to publish.
3. Always consider a null hypothesis. Always compare outcomes to what a simple model would generate.  This takes mental discipline. Henny Youngman in response to "How's your wife?" - "Compared to what?"  Gary Loveman, CEO of Caesar's on 3 things that'll get you fired "Stealing, sexual harassment and running an experiment without a control group." 
4. Keep the notion of deliberate practice in mind, and tailored feedback. If luck is a force, then pay attention to process. 
5. Make use of counterfactuals. Studying history gives you some insight into how the future might unfold. The problem is that you only see one of that paths that led to the present. The what ifs are less accessible. Hindsight bias causes you to explain the outcome as if it was inevitable. So, think about what could have happened but didn't. 
6. Develop guides to aid and improve your skill. We can hone our intuition if we practise intensely in environments that remain stable and linear (for example, swimming skill continuously improves because water doesn't change). The psychological requirement for investing is to develop awareness of the biases that affect all of us and developing techniques to mitigate them. Checklists : read-do and do-check types. First is a recipe for concrete action that is immune to unclear thinking. Measurement provides the basis for feedback. If skill is the key, then deliberate practice is the answer - use a coach. This is true no matter how good you are. Beware of belief system defenses.
7. Have a plan for strategic interactions. If you are the stronger player - simplify the game so your strength dominates. If you are the David taking on Goliath, then increase luck - create new battlefields - guerilla warfare. Use your space to get really good in one area and then beat the incumbents at their game. 
8. Make reversion to the mean work for you. Rate of reversion to the mean relates to the coefficient of correlation. No correlation means total reversion. 
9. Develop useful statistics. Predictive and persistent are valuable.
10. Know your limitations. Know the context. Know how the game and the rules are changing.