Here is a great page to come back to to reference clothing folds, wrinkles and drapery pictures. When you need to draw wrinkles or folds, it is easier to get a realistic drawing if you have something to reference.
Here is a general guide to drawing elderly people's faces and figures. A general age progression chart is provided below, and example illustrations for you to reference. Wrinkles are obviously added to the face, but other things change as well.