Scarlett looks old-Hollywood gorgeous in red lipstick. Why it works: she kept the rest of her makeup warm and neutral, which allowed her lips to take center stage.
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Worst Red Lips: Christina Aguilera
Note to Christina: unless it's Valentine's Day (or even if it is) pink and red shouldn't be worn together -- especially on your eyes and lips. When you go for a bright lip, keep the rest of your makeup natural.
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Best Messy Ponytail: Hilary Duff
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.
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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.
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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.
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.