hi looking at your render i see a couple of things that i think needs some tweaking and those are;

- the chest needs more detailing, try to model the collarbones or at least a bit definition around that area.
-there's something odd going on with the legs or are those loose sitting trousers,? i cannot see it properly .

The head seems to be smoother than the body part, if you are smoothing the body-part i would delete the half of your rough model and use a mirrored smooth proxy so you will see direct result.
Even when you will not be able to smooth the model in the end due to polygon-constraints i would use this, in my experience(as little as it is:p )it will result in very clean and well defined low poly models.
good luck