QUOTE(Mad Tom @ Mar 5 2008, 11:35 PM)

make sure before you start that you know exactly what you are trying to achieve by doing it, how you plan to achieve it, and how you will know when (if) you have achieved it.
For example, my practice this afternoon (on a Steinway D!!)
Bach inventions 1 & 8, Sinfonia 7
Purpose: warming up
Method: playing through, no stops or repeats or corrections
Achievement: When I reached the end
Scales and Arpeggios, randomly selected (using a random number table and an algorithm)
Purpose: To prepare for the Grade 8 exam by not knowing what is coming next.
Method: Start by playing each scale/arpeggio as if for an exam (i.e. no false starts or restarts) with as little delay as possible. Then play slowly hands separate (if appropriate) then very fast hand separate, then hands together at a comfortable tempo (currently about 110 for most scales, about 100 for most arpeggios but I don't ususally use a metronome whilst playing them)
Achievement: For each scale/arpeggio - when played through at correct tempo with no mistakes (note or fingering or timing) and as smooth as I can make it 4 times in a row. Any mistakes and it's back to play-through no.1. For whole section - When I've completed this for 12 Randomly selected scales / arpeggios.
Mozart K 309, short section by short section (check notes from last lesson - 10 particular points to work on)
Purpose: Varies section by section. In one section it is to get the notes accurate at approximately the right speed in ornaments. In 2 sections we changed the fingering at the last lesson so it is just to get the new fingering accurate and grooved, not necessarily up to speed. In another section it is getting the dynamics just right. In yet another it is the articulation that needs practice, and so on.
Method: In each case, "work on" whatever needs doing, at the right pace (whatever that may be, usually starting slow and varying through ridiculously slow to ridiculously fast and ending at the "right" tempo), hands separate & together as required until confident, smooth and accurate. Repeat short troublesome phrases (in one case 3 notes) repeatedly once right. If something is wrong, don't do the repetitions until it has been identified and corrected. Then re-integrate into the whole section. Try to play the last few notes of the previous section and the first few of the next section with each repetition.
Achievement: Move on when section repeated at least 4 times correctly (at the agreed speed, not necessarily at full speed or even hands together).
The warm up took about 8-10 minutes. The scales took about 20 minutes. The Mozart took an hour and 10 minutes. Then they closed the shop and I had to run for a train, or I would have done much the same with the Bach Prelude and Fugue and the Gershwin, some of which I will do now before I go to bed. If I had time I would also work on an older piece in order to maintain it in the repertoire, but that will have to wait until tomorrow!
Edit - I think this was a good practice. The man in the shop thought so too.