Try practicing clothing folds.
http://www.scribd.com/doc/5985013/Folds-in-Clothing
And getting rid of stiffness, try to do gesture drawings. Those help a lot!
Here are some examples. You can see the movement of the characters even though it is a still drawing. And no, it's not cause they drew multiple lines for each form that makes it look like it's moving, but look at the curve of the lines that have movement in themselves. If you were to draw a Straight line compared to a Curved line, which do you think looks like it has more movement? Obviously the curved one. So the key to preventing stiffness in characters is to try to add some curved lines in your drawings. A small bit of exaggeration is fine, but if you're going for a more cartoony/animation look (american cartoons), then you can exaggerate more. But exaggerating the poses and curves will help a LOT in helping add movement in your drawings.
http://farm2.static.flickr.com/1366/1331669394_c8703f3c50.jpg 
Reply
