When I was a kid I learned that you should cement your progress as you go. Practice and figure out how to do something correctly, and then stop and try to do that exact thing, correctly, nine times more. One person even told me to put ten pennies on my music stand and move one over for each correct repetition. I was told I should not go on until I had really learned that one spot. That made sense to me then, and it still sounds logical. I thought I would memorize the correct way to play by reinforcing it right away, but this turns out to be incorrect.

Instead, practice the first thing for three minutes, then the second thing for three minutes, then the third thing for three minutes and THEN come back to the first thing, the second and the third and then a loop around again a few more times. You don't feel as competent while you are doing it, but you are learning much more efficiently.

It turns out this is so much more effective than practicing the first thing for nine minutes and then thing two for nine minutes, and then thing three for nine minutes.

Here is a scientist talking about it: http://gocognitive.net/interviews/benefits-interleaving-practice