Staying up on my 3D chops means constant practicing and learning different techniques. As a self taught 3D artist I've had to take hours of time to learn how to model abstract objects and then learn the art of lighting properly to achieve the look I am after.
Take a look at this self initiated series of robots I created in Cinema 4D. Each bot started as a simple sketch then was interpreted in 3D from scratch. With each fun bot I created, I sought after learning a new tool or lighting technique in the program. I also made sure to keep the modeling process to under an hour so that I wouldn't get hung up on minor details. Enjoy.