People who excel at any skill use a technique called "deliberate practice" whether or not they know they are doing it. Deliberate practice includes these steps: planning (organize work in a structured way), concentration/dedication (higher attention span),
repetition/revision (strong tendency to practice),
study style/self reflection (tendency to self-regulate learning).

A rap related example from an article I just read:
"B.o.B. would practice rapping by writing out DMX’s lyrics on a sheet of paper, then hone his rapid-speech skills for hours. When he wasn’t reciting DMX’s words, he was crafting his own, sometimes in church, sitting in the pew while his father preached."

Hope this helps.

Best,
Patch
www.patrickpatchcarr.com