Bold criss-cross straps are the latest twist on the classic halter neckline. Eva Mendes wore a Temperley London dress to a recent N.Y.C. event. "I played with a simple and very wearable silhouette by adding graphic strap details," says designer Alice Temperley of the dress. The deco-inspired design has a "playful neck ruffle" to further emphasize a swan-like neck (and as a nod to the tuxedo them of the designer's "Beauty in Exile" collection). Consider fit carefully when trying this trend: the bodice should fit close to the body—without causing the straps to cut off your air supply!

—Betony Toht