Absolutely! Just as in real life, lighting is hugely important: A room lit by flourescent lights will look completely different than the same room lit with a handful of very low power tungsten lights.

To get half-decent renders (as thats what most of mine are - only half-decent), you need to have an understanding of the lighting, the shaders, and the rendering setup.

Have a look at Kevins free spotlight tutorial. Then buy a few points and download Mikes 3 Point Lighting tutorial.

This will get you started. When you get as far as you think you can go, post some of your images in the WIP forum and the real gurus here will do their best to help you out.