In this tutorial, I talk about my process for using ZBrush sculpts as blockouts for line art and some of the ways 3d is useful for concept artists. Follow along as I start a piece in ZBrush as a loose sculpt, then draw over it in Photoshop to achieve a clean line drawing.  
Then, in part 2, I color and render the piece using a cel-shaded style, but this time much more illustrative using dramatic lighting. I start from black and white line art and add layers for color, lighting and other details until the image feels right.