It's hard to judge unless we can see some of your work.  I only saw piece in your gallery, but your nude and it looked fine to me; I might of used more contrast, unless that is the look you wanted.  It's like anything else, it takes practice - my first 8 months was so uninterestng. I tried to study artist work that I liked, and also to develop my own style.  Wrong lighting, or no shadows makes 3D looks flat. I purchased the book Digital Lighting & Rendering by Jeremy Birn and it helped my work a lot.  I'm sure others will have different suggestion. 

Images that run around in my head eventually end up in my gallery.

Dragons like to have fun too!  Dragon Mischief Art