I am working on a set that heavily relies on cloth, I've looked around for tutorials but if there are any I've missed please put a link below. I'd like to learn how to make the folds and bumps in the cloth look natural and flowing in a hunter colored robe type of cloth. I use Photoshop, I mostly need help with understanding how to shade it to appear like loose cloth using different shading techniques. Any and all help is appreciated.

as well as study some textures.

google stuff like "cotton texture" "wool texture" etc etc