As an illustrator one of your jobs is directing the viewer's attention. If you don't give them clear instructions on where to look, they'll manage to do it wrong. The principle of emphasis involves using contrast to make your focal point pop off the canvas. If done correctly, your viewer won't know their being lead around your image.
If you want to practice yourself, here are the orcs to download. And make sure to check out the other entries in the "Principles of Design" series