18 Biggest Royal Wedding Guest Etiquette Dos and Don'ts

Before heading off to St. George's Chapel on the grounds of Windsor Castle on May 19, the guests of Prince Harry and Meghan Markle's wedding will all need to bear in mind at least 18 rules of royal wedding etiquette. If you're curious what they are, then pull out your favorite fascinator, shine your finest black shoes, and read on—because the big day is fast approaching! And for more amazing facts on the royal wedding, know that Here's the Secret Ritual Every Royal Bride Performs on Her Wedding Day.

The invitation called for women to wear a "day dress" and men to wear a uniform, a morning suit, or a lounge suit (basically a business suit). These are not suggestions; they are the rules.

Hemlines shouldn't be shorter than the longest finger when arms are held at the side and not longer than mid-calf. Dresses should not show a lot of skin. No bare shoulders and for goodness sakes, no cleavage. (Queen Elizabeth II is not a fan of spaghetti straps.)

British men love their morning suits and top hats. (Americans tend to look like Mr. Peanut in these unless they are in the wedding party.) Officers in the military should wear their dress uniforms. Every other man should consider an impeccably tailored Tom Ford or Canali suit in a dark color (navy is preferred). Under no circumstances should gentlemen wear linen. And speaking of luxury attire, here are 10 Great Ways to Wear a Navy Suit.

Though Meghan has rocked plenty of black since her engagement to Harry, the somber shade remains a color of mourning for British royals and should most definitely not be worn to a wedding.

White is reserved for the bride, and guest should remember that on the big day. Accents and patterns in those colors are fine, though. And for more on the bride, here are 10 Things We Know About Meghan Markle's Wedding Dress.

Hats are an absolute must for women attending a British wedding. However, there are guidelines one should follow: They are kept on inside the church, so they should fit properly and not be fiddled with during the ceremony. Fascinators—defined as small headpieces with bows, flowers, and sometimes a short veil—are always appropriate.

It's not the Kentucky Derby, so guests can forget about wearing a flying saucer-sized design, as well as anything with a huge brim. Wearing a towering creation that blocks the view of the people sitting behind you is just plain rude. Some royal women break this rule frequently (Princess Beatrice's hideous hat worn to William and Kate's wedding will live on in internet infamy), but they're royal—and you're not. And for more on royal weddings, check out the 2o Commoners Who Married Royals.

Commoners can leave the Birkin and other oversized designer handbags at home. A giant tote is sure to attract the attention of the security team that is on the lookout for any and all unusual items toted by guests. Besides, schlepping is very un-chic. Carry a small clutch like Catherine, Duchess of Cambridge always does. And speaking of clutches, know that This Is the Secret Trick Royal Women Always Do When Exiting a Car. 

Bare legs are frowned upon. Even Meghan wears pantyhose now. For more on the bride-to-be, check out these 10 Quotes That Prove Meghan Markle Will Be Running the Show After the Wedding.

The wedding is a formal church affair. It's also a day event, but it isn't a garden party. Open toes (even with a fresh pedicure) and wedges are no-nos. Slingbacks are also considered too informal. A classic Manolo Blahnik pump (like the ones Meghan always wears since her engagement) is perfect. Heels should be no higher than four inches. Sky-high stilettos are a bit much and are an unwise choice since there are lots of cobblestones to navigate around.

Men's shoes should be freshly polished and shined within an inch of their life. No brown shoes or belts. Black shoes are the only choice here.

Yes, Meghan is a former Hollywood actress, and the event is likely being watched by millions all over the world, but it's not the Oscars, and there's no red carpet. Guests should make sure their hat and dress are going to the same wedding. Don't wear anything with sequins. And for Pete's sake, don't wear anything that resembles a tiara. The Brits—not just the royals—have a lot of unwritten rules when it comes to dressing for a wedding. Follow them. At the top of the list: don't try to outshine the bride. In this case, it would be utterly ridiculous to try.

This is not the time to be fashionably late. Besides, guests will miss the best people watching of the year if they come in after the A-listers have been seated. Royal protocol dictates that the Queen is always the last person to arrive at the church before the bride and her attendants. So guests will need to get there early, relax, and take it all in. This is a once in a lifetime event.

There was no photography permitted at Prince William and Kate Middleton's wedding, and it's pretty safe to say it won't be allowed anywhere in Windsor (at the church and the reception) so, no royal selfies.

This is a good rule of thumb for all weddings (and any other time you are in a church). Imagine how mortified you'll be if all of a sudden "Single Ladies" starts blaring from your phone during the vows. If you're a smartphone addict, get some space from your device with these 20 Genius Ways to Kill Time without a Smartphone.

Don't touch any royal. It's just not done. And don't even speak to the Queen (not that there's a chance of getting anywhere near her).

There could be as many as 600 people at the reception, so the receiving line is going to be long and exhausting for Meghan and Harry. Say your congratulations and move along.

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We fought a revolution against the crown for our independence. Americans do not curtsy to British royalty. It's easy to get caught up in the whole British-ness of things, but don't do it because you'll look silly and fawning. For those that do curtsy, don't overdo it. Low, sweeping curtsies are best left to hammy stage actors. The proper curtsy involves a brief bob of the head and a slight bended knee with the weight on the front foot. Gentlemen are required to nod and look down briefly.

You may very well find yourself standing near some lesser royal or cross paths with the Duchess of Cornwall on your way to the loo. Stick to safe—and short—remarks about the "lovely weather" and "beautiful ceremony." Don't ask any questions like, "Do you think Prince Charles will ever be king?" For more on the royal family, check out these British Royals That Will Soon Have to Curtsy to Meghan Markle.

It goes without saying—don't get drunk. Don't even think about going drink for drink with the royals. They imbibe every day—and they drink a lot. Unless you're used to downing scotch (like Harry) or gin and tonics (like the Queen and Camilla) on a regular basis, opt for two glasses of champagne and then switch to fizzy mineral water.

What do you buy a royal couple who has everything? Nothing. Meghan and Harry have requested guests donate to one of seven charities they've selected representing social change, women's empowerment, conservation, the environment, homelessness, HIV, and the Armed Forces.

Don't even think of putting a champagne flute or a silver spoon in your purse (you won't be able to anyway if you take our advice and bring a small clutch). And forget about taking a centerpiece. This isn't your cousin's wedding. After the reception, Meghan and Harry are donating the blooms to local charities so don't purloin the peonies.

Unless you're Meghan's BFF from Northwestern and you 've deputized by the bride to share details with the tabloid press, save your anecdotes on the wedding of the century for Thanksgiving dinner with your in-laws. What happens at Frogmore House, stays at Frogmore House. For more on the Royals, check out these 15 Ways the Young Royals Are Changing The British Monarchy.

Diane Clehane is a New York-based journalist and author of Imagining Diana: A Novel.

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