This is more related to postwork in photoshop CS5, but most artists tend to use a softening technique on their poser renders which almost always makes it look much better than the default render. Here's a few tutorials on those and other basic postwork techniques:

http://www.youtube.com/watch?v=BsEC2PN5aNk

http://www.oferz.com/Tutorials/BloomEffect/BloomEffect.html