Did you see the image in my website's Galleries? http://www.punchhelpers.com/galleries00.htm
There are several resources that you can use, but IMO, lighting and shadows are the most important. Usually, I try several options before I create the final rendering.
Also, I will share a tip: in addition of the sunlight, add one or two lights (Electrical tab) => although the rendering will take more time, the shadows are more realistic.