I would say that brush size and opacity is key in obtaining a degree of realism.....If you look at the back of your part of your draped image I would suggest maybe just a suggestion of a fold is needed.  Where the cloth meets her arms I would say more discreet folds would look better. It looks as though you are combining your cloth images to make a finished article.....thats fine but, you will need to make sure your folds match each other.

Try this, make your shawl and position it where you want.  Then take the BURN tool and set it to HIGHLIGHTS, drop the OPACITY of the burn tool to make softer folds and increase it to make harsher folds. Also, make sure you have your brush set at the softest point.

My image shows the type of effect you may be looking for?