Consistent Pressure Gives a Uniform Look. Keeping a consistent pressure with the crayon on the paper gives a uniform, pleasing look. If you're pressing hard, your hands will get tired quickly, so I prefer to press lightly. Interestingly, being aware of how much pressure you're applying seems to be really hard for younger children. It must be tied to motor skills in some way. It won't hurt anything to tell them this tip, but if they aren't implementing it, just let it go.
In fact, taking a crayon or colored pencil to paper is a therapy method that dates back to the early 20th century _ though it seems people are just starting to rediscover its benefits. So how exactly does something as simple and seemingly childlike as filling in the lines lend itself to combating adult amounts of stress?