Anyway, what do you think needs doing to make it better?
Don't post jpegs.
Not bad at all for a first(ish) piece, with some nice attention to detail (the blood spatter looks pretty good).
For the following, left and right refer to the character's left and right-
Pallete: You've got about 50 or so colors (I can't tell if the jpeg artifacting is affecting this), but a good number of them are almost identical. You've done some hue shifts, but they don't follow any sort of discernable relationship.
Anatomy: His left thigh is shorter than his right, which makes his left calf longer than his right. Arms look like they may be different lengths. Chest and torso look too narrow to contain a ribcage. Right arm starts too early, there appears to be no shoulder. Head and facial features are misaligned.
Lighting: The black cast shadow, I would suggest lightening it, since it's currently so much darker than the shadowed areas of the body. It also appears to be cast in the wrong direction (seems like it should be angled to the back more). Right arm is receiving light from a different direction to the rest of the body. Right side of face is similarly lit. Add some specular to the blood on the floor, seeing as it's puddled and fresh.
