Indeed, Markel donned a pair of pantyhose for her first royal engagement since she wed Prince Harry on May 19. The Duchess of Sussex wore a white dress, wide-brimmed hat and tights on May 22 at the celebration of the Prince of Wales' upcoming 70th birthday.

"When I say wearing tights, I'm not talking about bright colors. It's very natural skin tones," he adds.

"It was kind of mentioned at the time, royal ladies should wear tights," Harrold tells CNBC Make It. "That's absolutely spot-on. And you'll notice, in recent appearances of the duchess, she wears tights."

At the announcement of Prince Harry and Markle's royal engagement in November, the future duchess was not wearing tights or pantyhose, as the press were quick to note .

Grant Harrold, nicknamed "The Royal Butler," has 20 years of etiquette experience. He's the former royal butler to Prince Charles, William and Harry, and his company Nicholas Veitch founded The Royal School of Etiquette and Butlers. Harrold shared with CNBC Make It the etiquette that Markle will likely have to abide by, now that she's officially part of the monarchy.

Still, Markle has been known to buck tradition (whether it's with her signature messy bun or hugging fans) so she'll also likely find a way to keep her identity her own.

So what does life and work as a royal look like now for Markle? Her royal duties range from attending official engagements to tackling philanthropic projects, all while remaining selfie- and social media-free. Plus, no dark manicures.

The royal wedding between Prince Harry and Meghan Markle might be as close as real life can come to a fairytale. And while the new Duchess of Sussex may get her happily ever after, she is also now a royal with royal duties and therefore is expected to adhere to special — and specific — protocol.

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Harrold notes that more neutral colors are also required for nail polish and makeup, and calls dark nail polish an "absolute no-no."

"It is the more natural look, it's not anything too bright," he says. "Same with nail varnish and makeup. It's always very natural, neutral, skin tone colors… you don't wear dark or black or gothic."

"They tend to opt to wear more sort of neutral colors, just not to draw attention to themselves, really," he adds.

Black is also fairly off-limits when it comes to clothing too. Black is the color of royal mourning, according to Harrold, so you typically won't see members of the royal family wearing it.

"Diana, Princess of Wales, on a couple of occasions, famously wore black," Harrold says. "So it's not written in stone that they can't, but it tends to be something they wear only when a member of the royal family or someone close to them has passed."

Staying social media-free

As an American actress, Markle's Instagram account boasted bikini shots and was filled with photos of meals, dogs and friends. And the lifestyle blog she founded, The Tig, shared her thoughts on everything from fashion to her favorite vacation reads.

But as a royal, you won't see her posting to social media anymore.

Markle shut down her social media accounts in January and folded her blog before the royal nuptials. Instead, updates on her life are now shared via official royal social media accounts.

"She doesn't need her blogs or Twitters or any social media, because what she says and does can be presented through the organization that she's a part of," he explains.

"The simple reason is, they don't want them to put something that they shouldn't, and members of the royal family…they don't get involved in politics or gossip or anything," Harrold says. "It's safer to have it all run by the palace."

Steering clear of selfies

If you happen to see Markle out and about and hope to snap a selfie with the Duchess of Sussex, don't hold your breath. Selfies are typically out of the question.

Harrold says the reason they don't do selfies is because the royal family doesn't position themselves as celebrities.

"They're not celebrities, same with autographs. Royals don't sign autographs," Harrold says.

"That's the difficult part for Meghan. She is, or was, a celebrity who's now a member of the royal family, so it very much changes for her," he adds.

But she will have her own voice

Royal etiquette, Harrold says, dates all the way back to the 14th century, but the Brits have also taken traditions from around the world and made them their own. The reason for such rules is rooted in setting expectations when it comes to behavior between the royals and the public.

"The reason that they're there, especially when it comes to royal etiquette, is so that people know how to behave around members of the royal family so they don't feel uncomfortable, and also so the royal family knows how to behave," Harrold explains.

"For example, now when Meghan meets a member of the public, she knows that she has to offer her hand first."

Markle will also be lauded as a role model for women; it's already been said that she will be a "beacon" and "someone that people look towards." On Thursday, Markle was named one of the top 25 most influential women in Britain, according to UK Vogue. That means Markle must hold certain standards.

And while the monarchy might put an emphasis on etiquette, Markle will likely keep her individuality.

"It doesn't mean to say that she won't maybe, perhaps come up with one or two of her own ways of doing things," Harrold says.

He points to the example of hugging the public. Members of the royal family traditionally do not hug, but Princess Diana would hug, and would get down to the level of children to give them a squeeze. Now younger members of the royal family tend to hug too.