you could start with soft cloth simulation let it drop of your model
then apply it at a certain frame to give a general shape
then use dynatopo to sculpt it to the shape you want
then retopo it to get a cleaner mesh and add mat and texture to it
I would start with a plane and extrude/model it to fit the BASIC shape/character you need. After, make sure the verts are evenly spaced and apply mutires modifier. Sculpt what you desire, then retopo (there are good tutorials on this, if you’re not sure how). I would keep it as a non-manifold mesh and apply a solidify modifier when you’re done. Boom, clothing!
There are ways and box modeling wouldn’t be the most appropriate imo. Have look at http://vimeo.com/26339130 starting from 13:00, then from the beginning ;).
Sure, cloth sim with modeling and pinning to dummy object before. Sculpt some, might give needed look.