Photographed by Raymond Meier, Vogue, September 2010

I grew up around relatives who believed the act of wearing denim or a T-shirt to the office was the equivalent of sporting a poster board asking to be fired. As a result, I tend to favor the safe (and sometimes boring) practice of uniform dressing, rarely experimenting with anything that could be conceived as particularly “casual,” or, you know, “fun.” (Let’s just say that I stick with things that read as “office-appropriate.”) This does not always seem to be true of my colleagues, who manage to sport all sorts of cool and creative looks, the sort that I always thought would make me seem insane or out of place. After a month of watching the way they artfully paired things like mangled denim with blinged-out sneakers and boys’ board shorts with blazers, well, I wanted to join my team’s Casual Friday philosophy. All while ensuring that I would not look like I had haggardly rolled in from pulling an all-nighter, of course. Or that I was disrespectful. Or slept in a park.

Suffice it to say, I am not yet confident enough to make these calls on my own: Earlier this week, I held up a sporty T-shirt salvaged from the boys section of a discount store with the outline of Michael Jordan dunking and asked my colleagues if they thought it would fly on Friday. One replied with a firm “no,” while the others immediately had recommendations for what to pair it with, ranging from a crisp, pleated miniskirt to skinny green cargo pants. Color me confused.

It is almost as if Casual Friday has become the new weekender look, especially in the creative field. This is not exactly the case in more corporate settings. “At my first job with a law firm in Paris, I remember wearing jeans to work (with an Anne Fontaine or Alain Figaret shirt, but in jeans no less) and that was normal. It was quite surprising to me when I first came to New York to see that people basically wore a uniform to work—a suit,” says Priscilla Djirackor, a lawyer in New York City who worked as counsel for a digital film-distribution company. “Even if it fit badly or looked unflattering, everyone would just put on a suit because that’s just what you wore to work.” Now Djirackor has her own practice with a client roster that includes artists and other creative talents, allowing her a little more sartorial freedom. A little. “In the summer I do wear a pair of hybrid track-and-harem pants by Catherine Malandrino. I also have a pair from a Korean designer that I wear with black leather sandals. They work perfectly on Fridays, but I wouldn’t imagine showing up at a client meeting—let alone court—with them. In my line of work, it just says ‘I don’t care.’ And that’s definitely not what you want to say.”

Whether you are in a corporate or creative setting, one faux pas covers all careers: Appearing disheveled and wearing clothing that is visibly low-quality is a definite no-go. And it’s no surprise that the look on Casual Friday appears like a potluck, exhausted-looking bricolage of items pulled from the closet at the last minute: Studies have shown that women put the most effort in on their work look on Monday, and that it is all downhill from there. Don’t be one of those women: The key to mastering Casual Friday is about being decisive. “Don’t look like you just rolled out of bed or did the walk of shame. If you’re going to wear a pair of jeans or a casual shoe, they shouldn’t look dingy. The ensemble has to be intentional and not just thrown on. You still have to appear like you put just as much thought into it as wearing a suit, but you just chose to go for comfort instead,” says Vogue Market Editor Kelly Connor. “Comfort does not equal sloppy. Additionally, you can look sloppy in an ill-fitting suit.” Noted.

As for what to wear, the look should be a balance: whatever is appropriate for your office only infused with slightly more of your personal style than you might wear on, say, a Monday. “A boyfriend jean should be worn with a heel or a heeled bootie to keep it from looking sloppy. A skinny jean should be in a darker clean wash and paired with a classic buttoned-up collared shirt. A blazer thrown over is always a good idea,” says Connor. “If you can pull off a legging with a flat, I suggest the shoe be a chic loafer, brogue, or pointed-toe flat, perhaps in a patent-leather to keep it looking really sharp.”

If your office is more on the corporate side, the casual counterparts to the pant and skirt suit are simple. “Both a cropped flared pant and a slouchy khaki pant are two closet staples that can be worn on a Friday with more ease than your usual suit. The best part?” says Connor. “They don’t require a heel when worn with an oxford shirt.” As for me, I’m beginning to branch out safely within the bosom of the home of fashion experimentation without fear of eyebrow raising. But no matter your industry, if you are ever confused about the fundamentals of Casual Friday, stick with that old saying: When in Rome, you can wear gladiator sandals if you want—just as long as your higher-ups are wearing them, too.