Oh, & don't forget postwork. Look at some of the best poser works in the gallery. You can be sure they've been postworked in some way. Whether it's for basic colour correction, filtering or after effects, it all helps to achieve realism.
My main point for postwork is to soften the edges on a figure & DOF. Look at a photograph, you'll generally find the edges around someone is slightly soft, subtle but effective. DOF is something I've come to like more for realism & it can vary from extreme to subtle. It's probably best to postwork this than to render it as it can take an age. Well, I know it does in Vue anyway.