I am a big fan of "The Hilfigers" campaign for Tommy Hilfiger. There's something very inspiring about a group this large, all impeccably dressed in classic American style, yet each with a look interpreted in a unique way. You can almost "read" the personality of each character, and pinpoint to whom you most relate.
Even if "prep" isn't your sartorial language, seeing how easily a single style can be interpreted should be inspiration for you to find ways to put your own spin on your personal pieces, tweaking them to pull together a style that's very apparently your own. A well-placed scarf, a headband, a blazer, a pocket square, a hat, a pair of sunglasses: any of these items can be the thing that brings separates together into a cohesive look.