#1: good environmental shot of this fella. Good focus on eyes, abdomen is a tad soft.
#2: good focus on eyes again. But flash is pretty harsh.
#3: Flash harsh, the whites are hot
#4: is oof.
Your flash need to be better controlled. Its very directional, and casting shadows that mask details. Its also harsh, esp on white subjects that tend to be hot if the flash is too strong.
Try to bring the flash to the lens level.