Nicole Richie's look

Is actually the hair cut. I used to have something similar. She has shaved layers. That's what gives the bob the volume and that curled under look you are looking for. Get a stylist that is good at razor cuts and you should be able to duplicate the look with no problem. Just take a picture. If the hair cut is done right, you won't need any product (maybe something on the roots for a little lift). It will take that shape on its own

Anytime girl.