If she is going to work on her own, make sure she is practicing in ways that she can be self accountable or like others have said she will just go out there and ingrain bad habits.
Jim's suggestion of taking swings in a mirror is a real good one. Also, as was mentioned I would have her doing a lot of Long T. You really only need wiffle balls, a T and a net. You can even work inside and outside locations in this position just by reposition yourself to the tee to simulate the different positions. The goal of course being to hit line drives into the net.
