Are you a Photoshop user? If so, I heartily recommend John Arnold’s tutorials at Photowalkthrough.com. He takes fairly ordinary images and, in these multi-episode video tutorials, walks you through what he does to them, why, and how.
This is fabulous tuitiion, but not for those in a hurry; each tutorial is typically in four parts of 20-30 mins each. But it’s time well-invested if you can get away from other distractions. I watched one on a long flight recently and learned a vast amount.