Hilary perfectly demonstrates what the messy ponytail this season is all about -- casual elegance. This style is a perfect way to look pulled-together, but totally cool at the same time.
Photo 5/11
Worst Messy Ponytail: Sandra Bullock
Sandra is usually a red carpet knock out, but this greasy, frizzy, I-came-here-straight-from-the-gym ponytail is just plain awful. When classic looks are more your thing, stick to what works, no need to get caught up in trends.
Photo 6/11
Best Defined Brows: Sienna Miller
Everything about Sienna's red carpet look here is stunning, but we give her extra kudos for showing how defined brows don't have to look forced and unnatural. A little strategically blended powder or pencil can enhance your brow shape and your overall look.
Photo 7/11
Worst Defined Brows: Megan Fox
Unless you want to look like a cheap pin-up girl knockoff (sorry Megan!) don't dramatically define your brows with a stencil, heavily line your eyes and wear candy apple red lipstick all in the same night. It's just too much.
Photo 8/11
Best Statement-Making Hair Accessory: Eva Mendes
Lovely Eva shows how a big hair accessory can be a great alternative to jeweled earrings and a necklace (and a heck of a lot cheaper!). Paired with a casual ponytail, this headband totally completes her look.
Red lips, statement-making hair accessories, tousled waves and defined brows are some of the most copy-worthy trends of the season. But just because they're trends doesn't mean everyone should try them -- as these celebrity photos prove. See which A-listers mastered the looks and which ones should stick to their classic hair and makeup styles next time.