As a reminder/tip, the behaviour of the rock is highly dependent on the release and the number of rotations.
Fewer rotations (a lazy handle) generally result in more curl and more rotations (a spinner) generally result in less curl.
As a rule of thumb three to four rotations from hog to t-line is a good starting point and consistency is key. Providing a lateral force to The Rock (setting The Rock) will also have an effect on its path.
Cornwall Curling Club Ice Technician