No, I never took any sort of classes beyond how to generally use Photoshop. I've only recently in the past year or so really started to get decent with textures, but it'd difficult with just a mouse. Most professionals use a wacom tablet or some sort of pen-based hardware which can really help.

All my textures are made 100% in photoshop. I use photo sources where applicable. The only thing taken from a photo on Duke here is the skin, flower petal, underside of his boot, and some of the seams on his pants and boots. I'll more than likely use a photo for the belt buckle and spurs, too.

Pretty much everything else is just using brushes; layer options for beveling, drop shadows, etc; and some filter effects... not too many.

Here's what I got so far. I know I'm using more textures than a real game would probably allow. ;P

EDIT: Removed old image.

Sorry for the size.