There's no short cut to anything in art.

The best way to learn is to draw from real life. Arrange some fabric and see where the folds go, how the light hits it and where the shadows go. Look at a human body and see just where the shadows fall, where the highlights are. Practice, practice, practice.

Same thing goes for clothing, but there's some good books on the subject. I like "Dynamic Wrinkles and Drapery: Solutions for Drawing the Clothed Figure" by Burne Hogarth