New Game of Thrones illustration in progress, for funsies. Andrew Loomis had a composition technique he used, where straight and diagonal lines broke up a page into unsymmetrical ways. The key was to make sure your lines intersected at various areas and NOT at halfway or thirds of the paper, to keep things fresh.
The hardest part is attempting to fit something into those lines and have them follow along the shapes you've created. It's a really great drawing challenge, though, and highly recommended to experiment.
You can read up on more of Loomis's techniques here - http://www.alexhays.com/loomis/Andrew%20Loomis%20-%20Creative.Illustration.pdf
Around page 34-36 is where he talks about composition!