For anatomy, bone structure dictates the shape a body should take. For example, let's look at the dragon.
First, on his right arm, his forearm (lower portion of the arm connected to the hand) is much longer than his bicep (upper arm connected to the shoulder). This type of anatomy is typically only seen in reptiles that walk on all fours, with a low center of gravity (think crocodiles).
Also, the dragon's chest puffs out while his abdomen is sunken back. This gives his spine the appearance of being curved and throws his center of gravity forward. This would support the fact that this animal is a quadruped (walks on all fours), and actually looks rather painful standing erect.
Because the animal is turned slightly, its wings should shift accordingly. Right now it appears that the wings are connected to the dragon's left shoulderblade and are on crooked.
For the dragon, I would recommend doing a Google image search for reptile pics to help with the anatomy, and for the ogre and human, I would suggest Googling images for human range of motion, just to give you a reference point.
I think once you clean these up and add some finishing touches, they will come out nicely.