This is my commentary on how I color my battle maps using Gimp, a free alternative to Photoshop. I focus mostly on the ever-important skill of layer management, and ramble a little about color theory too.

In summary:

• Isolate your line art
• Put your colors down on separate layers
• Put your light and shadow down on their own, top-most color layers
• Play around with your colors until satisfied.

This video features the Dwarven Outpost map.