Folding Dragon Wings - An introduction to A Theory (not a drawing tutorial, but preparation. :) )
Dragon wings are often based on bat wings... but this presents a problem. Bats tend to store their wings by wrapping them around themselves to help retain heat. Dragons, with clawed forlegs, might be comfortable doing this if they hung from their hind feet -- but generally, dragons are shown lying on the ground like most other 4 legged animals, so wrapping up in the wings would just get them damaged. So, they must fold them up something akin to birds.
I have a solution to the wing-folding problem. I arrived at it in a strange way, but I think it works. Basically, to figure out how a dragon wing works, I took a yardstick and held it in my hand (like it was the first wing-spar of a dragon's wing -- a finger-bone.) Then, I just tried to figure out the best way to carry the stick while keeping the end of the yardstick in my hand. I found that by tucking the yardstick under my armpit and elbow, it was well protected and easy to carry. So, I thought -- maybe dragons do this. You're probably not having an easy time picturing what I'm talking about, so I'll use The Art Thang again to illustrate. But, you should really try the experiment yourself.