The Making of an Expert (2007)

See also Bloom's two-sigma problem: https://en.wikipedia.org/wiki/Bloom%27s_2_sigma_problem

TL;DR:

Experts are always made, not born.

1. Practice deliberately — considerable, specific, and sustained efforts to do something you can’t do well.

2. Take the time you need — ability to attain expert performance is clearly constrained if you have fewer opportunities to engage in deliberate practice, since winning requires a training history comparable with that of other elite performers, nearly all of whom started very early.

3. Find coaches and mentors — development of expertise requires coaches who are capable of giving constructive, even painful, feedback, to extremely motivated students who seek out such feedback.

Real expertise must pass three tests:

1. Leads to performance that is consistently superior to that of the expert’s peers.

2. Produces concrete results.

3. Can be replicated and measured in the lab.