All really good points here. I have been doing quite a bit of 1HBH work lately and one thing my instructors have pointed out is the consistent drive through the ball on the swing. My preparation is good, but at times I tend to "whip" through the ball near the time of contact and this pulls my body back, forcing a cross-court backhand. While the shot is effective, it limits your options. If you practice consistent "drives", you will be able to have a lot more placement options. Also, I agree with many people in this thread: the supination should come naturally.
3X Wilson K90 w/Babolat Xcel Power 17 (Mains) & Luxilon ALU Power Rough (Crosses)