Disclaimer: Since I'm like a newb of CG, pretty much ignore my comment if you will, unless someone more experienced than me says "he's right". Also, I haven't slept in a day, so that might have affected my way of writing... like, badly.
Hi there, love seeing someone try a Star Wars Character. I've always been a huge SW fan, and played an Elder Sith in Star Wars Galaxies (MMORPG) for years...
That being said, I gotta agree with the others. It's your sculpt, and it's probably only my own taste. But, I don't dig the hood, it should have more mass. You might have to do that towards the end of the sculpt though, when the character is in pose, to have the robe overflow the silhouette of the character, and the hood make the face disappear... And I really mean disappear... Make it invisible, then go ahead and light up his lightsaber(s?) to make it reappear in a creepy red-reflected fashion.
On the armor, I don't really like the dragon thingy. There's really billions of established symbols in the Star Wars universe, but those dragons are not part of it. If you wanted to go for dragon, you could go for Khimogila or Krayt Dragons. But still I would omit the idea, and go for a more clear look. Lots of detail on the chest plate and the rest of the armor, but not so much symbols and stuff, this guys is not an Immortal from 300 or something. I'd make the chest plate only show layers of metal and that kind of stuff, more like a banded armor, if you will. And then, have one distinguished symbol piece, really stand out on top of the plate on one place (take FF7 Advent Children's Cloud for one example: http://img.photobucket.com/albums/v3...by_Sleepar.jpg The piece that keeps the entire armor together is like the only symbol thing in the entire armor, which makes it stand out so much.).
I'm not a professional artist (yet) and I haven't posted anything on these boards yet, but in my experience, what makes a CG character, be it in game or movie or other stuff, stand out from the masses is a unique design that doesn't overflow on those antic symbols you've been using, unless you go for a soldier-of-the-roman-army look. Take a look at what some of the best, in my opinion, are doing, Square-Enix. Their characters are almost always one nice composition of clothes of a certain style with very little design elements. Which makes those little things all the more recognizable. Vincent from FF7, if I had to think of something on his armor, it's a metal fist glove and those belt buckles around the top part of his coat. Or Sephiroth? 2 overlayed leather pads on each shoulder with 3 holes in them. Holes. That's all.
Okay, I've definitely lost track of where I'm going with this, but still, I recommend taking a break to think about a few single points on your sculpt that stick out and give it the unique touch you'll probably want, and make sure the rest looks so much like an assembly of real clothes that it makes cosplayers wet their pants...
Also, a quick google for 'Sith' showed up some nice images that you might have already seen, if not, go ahead and get some inspiration from them: