Is this done traditionally or digitally?
Because both types of improvements work differently.
If it was done traditionally, the goal is to not get better in terms of art, it's to get faster at drawing what you want since inking is harder to improve or to see what you're doing wrong due to lack of correction.
Digital on the other hand, you can't get faster as you're hindered by the speed of the pc you're working on and the time it takes the pc to process what you're doing.