Well I looked at some anatomy pictures online(or books), picked up some drawing books at my school.I tried to draw everyday(but now I'm failing one of my cles (-_- and well look a people and their clothes I observe. It sounds a bit weird but yeah, I try to take notice to everything ,shoulders, shape of arms, the muscles of the arms and body, and look at how the body curves, does it curve if so how and where. How your arms and legs bend for different angles do the muscles look different when they are bent or extended, check to see if anything is concealed by other body parts at different angles, such as arms, legs and the length of shoulders, are they shorter than another angle or are they the same shape is the face look different what about the neck, take these things to consideration(in other words try to notice everything).The folds in the clothes often happen were the body bends or pull on the clothing I am still practicing the folds my self so I can't say much, watch some Youtube Vids and people, look at your self raise your arms and look art your shirt is there creases if so where and why look at it and think about it, ask your self why did it fold right here and not here also look at the shape of the fold. That's about all I can say because well I still gots lots to learn Too I hope this helped

Thanx dude