try the pose again, for the mirror, and you'll discover one of the rules of balance : when the knees are bent and there is no other support the breast will never pass them without causing a fall. this is a rule of drawing a person running at topspeed, when this rule is broken (locomotion being nothing but small leaps and controlled falls)
dump the dither on the head else he'll have pockmarks all over his bones, typically considered a no-no for living things. Then of course, having a skull for a head is also a bit of a no-no, isn't it?
Also i flettened his body a bit, which i would correct but you get the idea about the pose and the skull anyhow.