Look at the world. Don't assume you know what a thing looks like because you are probably missing a lot of details. Look at things. Study the way light affects objects and the world. Look at what it does.
Great lighting can make a box on a plane look good.
And you don't need radiosity or fancy plugins or brand new rendering engines, you just need to be observant. If you're not observant about the world, all the technology in the world is not going to help you. For me, very. I always do many sketches, of individual objects, compositions, whatever. It helps me know about things, and about images.