First off let me say a few things to consider if you really want to get into the game industry. (From my own experience in the graphic design industry, and the things the professionals keep saying on sites like
www.cgtalk.com)
Yes! You definately have to start on non-StarCraft stuff at some point! The entire creative industry, whether simple logo design like I do, or the far more artistic game or movie industries - is all about coming up with different and new ideas.
Additionally you'll learn more by doing 'original' artwork as it's also called - A protoss is something we already know the looks of, or can find some reference for, but doing something from scratch forces you to think out of the box.
As for Constructive Criticism
You have an exellent attention to details in both the line art and pencil shading.
My only critique, is that I noticed they have little to no perspective on the faces - ie. they are 'flat' sideviews.
(Kinda like ancient egyptian paintings, where peoples faces are only seen from the side, no matter what the body pose is like)
You certainly have the skill, so moar perspective plz!
