Zimmerman outlines the key components of expertise. Each of these components is a necessary but not sufficient condition for development of expertise.
He also elaborates on the differences in self-regulation practices of experts and novices.
Source: Zimmerman, B. (2006). Development and adaptation of expertise: The role of self-regulatory processes and beliefs. In Ericsson, K.A., Charness, N., Feltovich, P., & Hoffman, R. (Eds.), The Cambridge handbook of expertise and expert performance (pp.705-722). Cambridge, MA: Cambridge University Press.