Elements of Practice

There seem to be several elements to practice:

Sheer repetition – Malcolm Gladwell says research show about 10,000 hours, consistently in many different fields

Challenge – doing something you can already do well doesn’t help you grow

Feedback – practicing something wrong will make you expert in doing it the wrong way

This article on The Making of an Expert from the Harvard Business Review is a good overview (from a very unmystical standpoint.)