Well firstly, why not embed the picture onto the page? like so



Secondly, what is it?
And what was your referance.
If it is what I think it is, then look at skulls and how yours compares to what you see.
If its an alien, then maybe a bit of facial anatomy, as you haven't defined the mandible right and you need to define the cheek bone.

That and that you show potential, but you haven't submited art that would show that potential.

Things come as you learn them, shading lighting and so on need to be learn't.
Basics really, go on the main part of the site or rescources and look at tutorials, also have a look at pixelation