It's official: tough girls are the season's It girls. Biker chic style—think punk accessories and lots of leather—ruled the Fall 2013 runways, from Phillip Lim to Versace. But how to wear it so that you look more Kate Moss, less Harley Davidson? We've rounded up the best biker chic fashion, plus expert advice on how to wear the trend. Bottom line? If you buy one piece this fall, make it a leather jacket.