Three words:  Three point lighting.  Do a search on google for three point lighting and you will quickly find out how photographers use light setups to achieve eye popping results.  With any 3d app, you must work the lights and shadows like a pro photographer other wise your results will be no better than if you used a poloroid.  Learn about lighting, then start tackling textures, scale, POV and composition.

Post lots of your images and absorb as much criticism as possible.  DON'T pay attention to the "excellent, gorgeous, the best I've ever seen" comments.  Pray for someone to be honest and point out where your images need work.  Look at lots of others work and see what makes it work and what makes it flop.