Taking drugs to overcome nerves is the thin edge of the wedge going in there.
Being unprepared heightens nerves.
It is normal to be nervous.
Never just run through a study because you happen to be familiar with it, but use it to see what you can get from it on this new day which has been granted you.
I use the traditional Moyse scale books slightly modified.
I think it is most important for a teacher to play the pieces and studies that are being played by the student.