[danielsangeo]

Originally Posted by Obsidian

I'm very unfamiliar with layers

Here's an easy way to visualize it. Imagine taking transparent sheets of paper and drawing on them. You can stack the transparencies together and create what LOOKS like a single image, but you can move the individual transparencies around without affecting the other transparencies.

This is, in essence, what layers are. You can put the line art on one layer, and then put colors underneath it, so that the colors go "under" the lines, creating a clean look without halos (assuming there are no halos on the line art layer to begin with).