While looking forward before locking onto the ball on the tee is helpfull. Teaching them to see the exact spot you want to make contact with is very simple but extremely effective even with drops and rises. Make it as simple as possible and success will come more easily to the student.
To add to their and paying attention I will put forward and backward spin on the ball as I soft toss. Then I will spin it so the spin is off axis like a junk pitch will look by using my thumb.
I also like to vary the height of the ball however I never raise the ball above eye level as it is not what we would see in a game.
Thanks Howard