Looks like a good job to me so far, there's no high res so must guess here but it's always a good tip:
Create a new layer on top, select "sample all layers" take a small (2 or 3 pxl) soft blur brush (set the strength to 60 or so) and go over the edges of the parts you've added, this makes the blending look much better.
But so far great job, you added reflections on the helmet (transparent part), the angle of your face is good enough (might been a bit better but it's good), shadows look good. Maybe the colour of the face is a bit off, might need a bit saturation but that's hard to tell without seeing the hig res.

from me.
Creativity is the sudden cessation of stupidity.