There are few things more challenging (or potentially humiliating) than finding an outfit for "business casual" attire.

While most companies descriptively outline their formal dress codes, very few write down the rules of "casual" dressing. This may lead you to ask such questions as: Are open-toed shoes a no-go? How short is too short? Are jeans ever acceptable--and, if so, what's the best way to pair them?

"The challenge, first and foremost, is that nobody ever describes what business casual really is," says Sylvie di Giusto, a corporate speaker, trainer and image consultant based in New York City. "People think that 'casual' means, 'I don't have to care.' It actually means the opposite."

Here are four expert tips on how to dress for your next "business casual" event: 

1. Dress down, not up. 

The most common mistake that executives make, di Giusto says, is trying to make it work.

"If you're trying to make it work, it's wrong," she says. "What you should do instead is take your professional business outfit and think: 'What can I skip today?'"

When wearing a suit, she explains as an example, you should remove the tie. Pair the rest of the outfit with a white shirt and oxford shoes instead. It's OK for men to wear denim--provided they balance it out with a dress shirt and sports jacket.

2. Ask yourself three questions before getting dressed.

What you wear is about much more than your personal appearance--it's a way to represent yourself (and your company) in front of key contacts. 

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Before getting dressed in the morning, di Giusto recommends asking yourself three questions:

1.) How do you want to represent yourself?

2.) Who else do you have to represent?

3.) Who is going to be there [in the room]?

These context clues should help you determine whether or not a slightly more informal piece of clothing -- a hoodie, for instance -- could work. (A room full of lawyers? Probably not. Silicon Valley expats? Perhaps.)

3. Avoid distraction at all costs.

Generally speaking, you'll want to avoid loud colors and materials. And when it comes to hair and makeup, less is usually more. 

Women, di Giusto adds, have a harder time of it than men, simply because they have more options: Dresses, skirts, and jump-suits abound, which can make getting dressed for work "confusing." 

"The risk that women choose something wrong is much higher," she adds. A gaping neckline, or a short skirt, has the potential to make or break your first impression.

She gives one helpful rule for length: Using your thumb and pointer-finger, measure the distance up your leg from your knee. An appropriately cut, 'business casual' skirt ends where your thumb does. 

4. Only deal in high-quality fabrics. 

No matter the context, you should steer clear of synthetic materials. 

"I have a zero polyester rule," says di Giusto. "You have to show quality in your fabric choices, and polyester looks cheap... because it is cheap."

For better alternatives, go for cotton or wool.