Heh. It’s christmas, time to give and share! 
Good to hear that you take this as a learning curve rather than just another tryout and moving on that I’ve seen too many times happened here.
But anyway, it starts to have the shape but there’s still some minor “offsets” about lenghts, volume and curvatures.
I made a quick example where you can compare your model to one I found from the web. If anyone can point out who’s model that is, would be super because I couldn’t find the original author for this.
But to the point.
- I marked some pinching issues you should take care of before moving on because those are going to make your life harder later on. I’m also not so sure about that topology you are using on your model. It also can make your life harder to have wrong kind of topology to start with.
I posted (4.) an example of good start point where basicly all the needed forms are already in the topology, that helps a lot while sculpting cause basicly you only need to “push” the shape out. And it’s much more easier to see where you are going at. With wrong topology, it can throw you off from the right course cause you don’t have any clear landmark where you are going at.
(4. is a model that can be downloaded some where here in zbc, I just can’t remember where.)
And I wouldn’t worry too much that fact that “This isn’t my original model” because it is much more easier to learn from a good subject than making thousands of wrong ones. After you have played around, the key elements about topologies and shapes have burned in your memory and then it is the time to start making your own one with clear and solid knowledge of the basic stuff.
I also marked some key shapes from other angles to help and guide about those biggest forms that builds up the shape.
I also put those silhouets on top of each other to see the difference on forms.
The quality isn’t the best but it’s darn hard to draw with a mouse! 
Lastly I also made this grid to compare your model to the other one to see some mismatches by that. I think that the most obvious ones are the shape/ wideness of the shoulders and the arch of the legs. Normaly the legs kinda archs inwards and yours pulls outwards.
Your arms actually looks good, and I think that the mismatch has something to do with the poses that they differ from each other. Not sure. But those shoulders need some tweaking.
Phew! So there’s my ten cents! Hope this isn’t too overwhelming, but I wouldn’t bother to put this much effort on helping some one if I wouldn’t see the potential to one actually evolve and become better in this subject.
And almost forgot, I usually exaggarate the shapes and forms to see them better while i’m sculpting and when I’m done, I just start to smooth them out if necessary. But I think that everybody has their own methods that suits for their workflow.
So good luck and cheers! 
Also, you can check out some breakdowns from my own projects where you can get a little bit sense of how I do stuff myself:
http://www.zbrushcentral.com/showthread.php?t=86595&page=2&pp=15