This entry in the Principles of Design series explores the idea of a visually balanced image. Though hard to quantify, most people are able to tell when an image is unbalanced. Generally they don't know how to explain it, but the image seems 'wrong' somehow. As an artist, it's important to create balanced images!
If you want to try out the techniques in the video with some orcs, make sure to download them here! I will warn you -- the file is a relatively large .PSD, so don't be surprised if the download takes a few seconds.
Also, it's important to know that I did not invent these principles! They are extremely old and well documented, so make sure to find other resources to explain with more depth. Photography books seem to be especially good at some of these concepts, as well as "Framed Ink" (my current favorite book on composition). And make sure to check out the rest of the "Principles of Design" series!