The reason you track your hand's path is to help track your rod tip's path. But more importantly, you do these things to track the line's path.
By all means work on your hand's tracking and tip's tracking but in the end use these in conjunction with your eyes to work on the path of the line in motion. I've found the best results in getting my hand to do what the line tells me to do in order to track it straight.
Get the line tight end-to-end before putting it into flight on the backcast. A tight line travels in a striaght line.
When reversing the backcast to the forward cast, use your eyes to watch the front portion of the line (near the rod) to level it out horizontally / parallel to the ground as you come forward before you put any power into it.
Stop the rod tip close to the straight path you made with the front of the line as it's coming forward, the closer you stop the tighter the loop.
Good luck and stick with it.
IFFF Certified THCI @ 2005
Capeflyfisher Guide Service
Island Hopper, Guitarist, Incurable Dreamer
and Founder, Worldwide Flyfishing Forum