From Willingham's Why Student's Don't Like School:
To be a better teacher, one must: (1) Increase space in working memory (chunking, making process more routine, so that other things can be thought, i.e. once we've learned how to drive, we don't pay as much attention in working memory as we did when we first were learning), (2) Increase our relevant factual knowledge about teaching, and about our subject area, (3) Increase our relevant procedural knowledge.
To be a better teacher you must practice (some teachers level off in practice and skill after 5 years or so...
Practice means: getting feedback from a peer, doing things not related to the task (exercising, eating well), watch teaching tapes of others, comment on tapes (yours and others), bring one new thing back into the classroom.