This is just a question for donjuan. He mentioned in his previous post about the position of the elbow, and how that guides the position of the hands and helps hitting wrong notes. I was just wondering if he could elaborate a bit on that. Thanks. I don't have a teacher either.
I feel kind of like I'm plagarizing, repeating my teachers words... but anyway, Im sure he wouldn't mind. If anything, he would be mad about me screwing up the description and telling you to do the wrong thing!

anyway, be warned..
Ok, so what I write here mostly applies to passages like scales or arpeggios, where the hand has to get from position to position, and it seems like it has to be done in a hurry. The problem is that hurrying sacrifices optimal support. Therefore, try to find hand positions so you can turn, say, 16 individual notes into 4 comfortable hand positions. So then you learn the notes in the hand positions. The hardest part is combining hand positions, which I find easiest way is to jump to the last key of the position you are trying to get to.
That sounded confusing. Let's take an example, say when you want to play a descending C major arpeggio, starting at the *:
C D E F G A B C D E F G A B C D E F G A B C
1 2 3 1 2 3 1 2 3 5*
{ } { } { }
Hand positions are indicated with {}. Here is the problematic change from one position to the next:
F G A B C D E
3 1 2
} {
Instead of going from C with the thumb to G with the 3rd finger, try to go from C with the thumb to the C an octave below, with the thumb:
C D E F G A B C D E
1 1 2
} {
If you practice going from thumb key to thumb key, you are training to be ready for the next position without even trying to be. However, this requires a nimble
elbow to be comfortable. Eventually, you will be catching the G and E keys while your thumb shifts from C to C. Just don't think about going from C to G, because that is slow and awkward, as you are running out of fingers, and your wrist is getting all twisted up.
The wrist's position is dictated by the elbow, and the elbow to the shoulder etc. anyway, if the elbow stops working (gets all stiff), then the wrist stops working, and the fingers try to stretch uncomfortably during hand position changes, and it is very easy to play notes you dont mean to play by accident. This is why you should pay attention to your wrist when you play wrong notes; so you can find the cause of your problem, whether it be a stiff elbow or whatever.
I hope I explained it somewhat successfully; My teacher can do much better in 30 seconds by showing me at the piano. Anyway, I am just explaining it the way I understood it. I felt that it helped me eliminate that feeling of rushing and sacrificing right notes for rhythm.
donjuan