Yeah, neat idea with the albino skin. I think the colors you're using look great.
I actually don't mind the dark blue on the collar bone. What I think you need is to extend that up on the inside front of the trapezius. Basically along a straight line from where the shoulder meets the collar bone (that little dip) to the top left corner of his mouth (and then shade in the area to the right of that line). I'd also use that shade on the left side of his face (well, his right side) under the cheek and along the side of his jaw. Not much of what you see from the front view, but if you turned him 90 degrees then you'd see the area I'm talking about. With that head tilt I think you can use some strong shadows on that side of the face.
I think the issue with the dark shade as it stands now is the transition is too stark. I'd work in at least 2 or 3 more intermediate shades to help it transition from that dark shadow to your lighter skin tones. The more intermediate shades you use the smoother the transition will be, so use as many as you feel comfortable with. If you can do 5 or 6 that's even better, but at least 2 or 3.
While not as critical you can also work on the transitions on the back. I wouldn't make the crevices between the muscles any darker (you could even go a little lighter if you wanted). But I'd do a more gradual transition from the bottom of each of those shapes. They're all pretty rounded shapes so shade them like spheres (more or less). Going from the bottom I'd take the transition tones (between that dark shade and the light one) up about 1/3 of the way before I get too light. Keep the tops bright and then go right into the dark shade for the bottom of the next shape. I grabbed this shading sphere image off a google search to help illustrate what I'm talking about. You've got that core of the shadow tone and then just too quickly to highlight. Work in that middle region to help define the shapes.
View attachment 29354
Ignore the cast shadow and reflected light part of the diagram. But the rest is a pretty good guide as you work on the figure. You can think of most organic shapes as just spheres (typically stretched or squished, but still more or less just rounded shapes).