This is the piece of professional clothing you need to invest in

Unless you're Mark Zuckerberg, dressing for work is complicated. Men have a standard pants-and-shirt work uniform that works in almost any office environment (plus or minus a tie or a jacket), but women have many more options — which isn't always a good thing.

I, for one, have not cracked the code yet.

In my seemingly endless effort to build a wardrobe of clothes that fit well and are at least semi-stylish, I have amassed an array of cheap clothing options that all seem like they could work when paired right — emphasis on the "could." A particularly low point was when I wore what I believed to be one of my fancy dresses to work, and a co-worker asked if it was a "grandma sweater."

Faced with fast fashion's ever-rotating lineup of colors, fabrics, prints and styles, it's all too easy for professionals to make the same mistakes I have.

To improve my shot at success, I brought in a professional to guide me. Tiffany Yannetta, shopping director for fashion website Racked.com, reviewed my wardrobe to determine what works and what doesn't.

She didn't hold back. More importantly, she answered my biggest question: What is the one piece of clothing every professional should invest in?

Her answer: A good blazer.

"Buying a good blazer is important because it's such an easy way to elevate an outfit," Yannetta says. "The upper half of your body is what people see the most — more than your pants or your shoes."

Expect to spend roughly $90 to $200 on a quality garment that fits perfectly, she says. And if a high-caliber item still needs a tweak, spend the money to have it tailored.

Spending that much on one piece of clothing may seem like a lot, especially if you're a millennial who's still dealing with college debt, like I am.

But if you look at cost-per-wear, it actually is worth it.

Take the example of a blazer on the more expensive end of the spectrum, one that cost about $200. Maybe you bought it for less and had it tailored for that price, or maybe you found a great fit from a high-end store.

If it's a wardrobe staple and you wear it twice a week for the whole year, that's 104 days of wear. Divide the cost, $200, by the number of days and you end up with less than $2.00 per wear. Not a bad deal, especially if you feel great in it.

Compare that to a cheap blazer that costs $39.99. It's much less likely to fit well and maintain its shape over time. You'll pay a smaller price up front, but are less likely to look and feel stellar. You may even need to replace it entirely, spending additional money unnecessarily.

"A good blazer, if you take care of it, can last you years," the expert says. "Plus, you can wear a blazer with literally anything: Over a dress, with trousers or jeans, and with a T-shirt or blouse under it."

Here are Yannetta's 5 tips for finding a great work blazer:

Make sure the sleeves are not too long. Having long sleeves is a "dead giveaway" that a blazer is cheap and doesn't fit you well, she says.Pay attention to the way the blazer sits on your shoulders. Make sure it's not too puffy or large.Look for stiff material, it looks more expensive and will usually fit you better.Shop for one in a "neutral" work color such as black, navy blue or gray so that you can wear it with many different pants.If you can afford it, have it tailored.

"A blazer becomes the focal point of the outfit, so having a good one — one that fits really well, is flattering, and a nice neutral color — is key," she says. If you're working on a budget, she recommends shopping around holidays like Christmas or July 4th.

"Always look for a sale if you can find one," Yannetta says, "but a blazer is something you should definitely spend a little bit more on."

Video by Jenny Catherall and Eren Gulfidan.

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