stuh505 ~
hey dude 
thank you so much for your appreciation!
really need it as this artwork will get tougher along the way …
that is one sexy piece of work
… you can seriously take it to the next level if you refine the areas some more and do a little color filtering with the help of layer adjustments … [ curves … color balance … ] … always keep reference images with you to check out certain parts of the body that have strong skin folds … protrusions … muscle … etc
as for the shading … i use a soft brush for blocking … then for pushing / smudging some parts of the shape … i use a soft smudge brush with a value of 75 …
the smudge tool allows me to work on some areas … as compared to the gaussian blur filter which will blur the image as a whole … ( unless if you use a feather selection ) … but i feel the smudge tool gives me more control … great example as mentioned in my previous posts : area shadows … which has become like a concept for me … from then on … i started to smudge paint in that manner …
i know it sounds weird … but, believe me … it taught me a lot …
check these out …
http://www.foro3d.com/attachments/159401d1329410270-iluminacion-conceptos-generales-areashadowshd7.png
http://static.photo.net/attachments/bboard/008/008kTO-18649784.jpg
http://www.win.tue.nl/~wstahw/2IV05/Area_light_source_soft_shadow.png
notice the dispersion … very simple terms : hard to soft … in to out …
use the smudge brush that way … be gentle with it … using a hard round brush … just paint a blob … use the soft smudge brush … start from the edge … but dont go all the way … then compare with the ref images …
and as for the 8 bit posterizing nightmare

lolz! oh man … we’re in the same boat for sure
… i’ve faced it a lot of times …
but you know what … it’s the smudge brush yet again that will help you out 
my latest work “droid red” had insane amount of banding … so i kept it that way for the time being …
after all the mods / tweaks / fix ups were done … i copy merged the entire file … pasted it onto a new layer and then with the smudge brush … i used a strength value of 2 or 3 … smudged out the posterized areas …
i created a test psd file for you and included the brushes as well 
here it is : http://www.2shared.com/file/g8LlYSym/blend_test.html
there is a soft blend brush and a hard blend brush … go nuts experimenting … it’ll get rid of the banding … and further more it’ll give a subtle texture / grain … rather than a smooth all plastic feel to the image …
play with the scattering and spacing values for extra dispersion …
but most importantly … it’s the smudge strength value … don’t go beyond 5 … your image will look too patchy …
also, only use this brush for the polishing stage . coz you need to work on a flattened file else there will be lot of layering … more banding as you work … it’ll be crazy trying to fix it up over and over again …
[ hope i didn’t repeat myself … or drive you mad
]
please experiment … and if you still didn’t get it … do let me know … i’ll be out of station for a few days … so when i get back … i will try and do a video 
take care!
enjoy mate!