Sienna Miller is often credited being one of the key fashionistas that ushered in boho chic as a style. The actress, who also fronts her own Twenty8Twelve fashion line, is a new mom, yet she still retains that signature, artfully messy style that has made her a fashion darling for the past decade.

Miller's dresses --even her LBDs-- are usually unique, like this retro-inspired Topshop number.

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She remains trendy, looking effortlessly pulled together in dark skinnies, grey booties and a big, furry brown coat in NYC.

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But the actress, who once played Youthquaker Edie Sedgwick, doesn't always nail it when going casual and boho. Exhibit A: This clingy, heather grey dress, which just looked sloppy. Boho? Yes. Chic? Hmm, only in the accessorizing. We'll give her that much.

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What's Right:

The Burberry spokesmodel donned a clingy, straight skirt with a furry top. It was chic and fashion-forward, and true to her boho chic aesthetic.

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Miller wore a body con, cream-colored Burberry dress topped by a studded leather jacket at the 2013 Met Gala, which had a punk couture theme. She didn't take the concept too literally. She got it JUST right -- complete with bedhead -- as the overall presentation fell in line with her personal style. On anyone else that doesn't practice boho chic, this would have been a "try hard" moment.

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Miller's cream cape dress was eerily similar to the Tom Ford dress Gwyneth Paltrow wore to the 2012 Oscars. Copycat or not, it looked great on Miss Miller.

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The actress wowed in this tailored, sophisticated black dress with a slit that almost mimicked a pantsuit.

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This lacy, seafoam coat-dress was incredibly Kate Middleton and a knockout for Miller.

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What's Wrong:

This Erdem two-piece looked like Grandma's table cloth. Ugh.

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A pantsuit can go either way on a fashion plate. In this case, it went south. The loud, floral pattern and loose construction compete for the eye and did nada for her figure.

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Another jumpsuit gone horribly, horribly wrong. The crimson color added pop, making the overalls vibrant. But Miller ended up resembling a house painter.

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While we love the coral-red shoes, this outfit comprised of separates aged Miller. For someone so funky in her fashion, this was out of character.

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How to Fix It:

Miller should not deviate from the boho chic vibe that made her a head-turner in fashion in the first place. She can adjust and adapt to trends and her age, like she did with this floral and lace Dolce & Gabbana frock.

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The actress has a slim figure, so anytime she pours her body into an LBD, even in a simple pencil shape, she stuns.

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Layering is an essential part of the boho chic look, but this roll-outta-bed ensemble was sloppy and ill-conceived. It's as though she grabbed whatever was in reach and threw it on. We understand that not everyone is camera-ready 24/7, but Miller is famous and a style star and therefore we have standards to hold her up to. For the most part, she lives up to the status she's earned as a "best dressed" starlet.

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Miller also has an eye for tailored pieces, like this structured pink dress. It's still unique, thanks to the bedazzling and satiny fabric. It just "fits" Miller's style and when she adheres to twists on her own aesthetic, she wins.

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