There's ton to be done before rendering (modeling proper corner radii, adding part lines, creating realistic materials, choosing dynamic lighting/environments, etc.) to set yourself up for success. After that treat your renderings the same way you would a photoshoot. Set up your lights/environment to get all of the highlights, shadows, and reflections you need, even if they don't all come in the same shot. Render a spectrum of options. Composite your shots, tweak your exposure and color balance, add or remove noise... Just like every photoshoot has different post-production needs, every rendering does, too.
Reverse engineering reference photos and renderings can really help, too. What camera angles are they using? Where are their lights? What kind of background do they use? Shadow, reflection, or both?
Finally, be aware of the telltale signs of the rendering program you're using. The default options and environments on Bunkspeed/Keyshot, for example, tend you give you this grey, cloudy blob for a shadow that can be a dead giveaway of a rendering. Working to eliminate things like that will not only give you a more photoreal look but help to push you toward more dynamic images in general.