Jesus, I'd have to write a book. Sorry, I didn't mean your skills on Maya, or normals or anything like that at all. I meant your artistic eye. There is a discussion on jay's new character about what we see and what is really there. Often if you measure against negative space rather than from the particular part of the model you are creating you will find discrepancies. Calligraphy relies heavily on negative space for its aesthetics. Check out some Chinese calligraphy, look at the empty part of the page and the part that has the ink and see how they form one; positive and negative to create the beauty of the art form. This is a perfect example of p and n space.

A far as your model, very slight changes will pull all the parts into correct relative positions as a whole (is this making sense?) the shoulders, he angle of the armour compared to the body, in relation to the face, all these things will be easier to put into correct and relative position when you understand negative space. It is a way of measuring on thing against another to get correct proportion.
The jpeg is not so much about P and N space but is something that would be quickly noticed when you understand the relationship between what is there and what is not there. We see what we want to see even if it is not there, that is why it is important to understand what is not there?? good luck with that rave, its the best I can come up with at the moment but keep asking or try to find an art book called 'thinking with the left side of the brain' something like that, it's famous anyway. Pand N space is relative o what area of the model you are working in or on.