TREND: Tweed

WHO'S WEARING IT: Sienna Miller (Rag & Bone), Jessica Biel, Blake Lively (Smythe)

HOW TO WEAR IT: Tweed brings a fall element to any outfit. Just look at Sienna's shorts! While similar ones are available, we prefer the sleekness of Jessica's pencil skirt. And we love how Blake made her boyfriend blazer edgy with leather pants. Since the material never goes out of style, it's OK to splurge on a coat or classic pair of pants.

Or, shop the steals 'n' splurges below!