Whether it’s all those cooking shows on TV or spiralling restaurant prices, the at-home dinner party is back in vogue. But how do you throw one or, at least, attend one and still be welcome next time?

Lizzie Post, the great-great-granddaughter of Emily Post, who in 1922 wrote the book on manners – Etiquette in Society, in Business, in Politics, and at Home – has helpfully come up with a dozen do’s and don’ts for modern-day dinner party hosts and guests.

Post, who co-hosts a podcast on manners called Awesome Etiquette, told Vanity Fair magazine she thought her great-great-granny would have enjoyed modern society.

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“She would have loved the sharing of photos with family and the like,” Post said. “But I think she would say what we say, which is that when it gets too personal, it’s a problem.”

Here are Lizzie Post’s new dinner-party rules for hosts and their guests. Stick to them and you’ll be on everyone’s dance card:

Do not arrive early: Post says this is never to be broken: “Walk around the block, go pick up some fresh flowers, anything. It is rude and it puts your host in an uncomfortable position, so whatever you do, do not arrive before the time listed on the card.”

If you are running late tell your host the truth about when you’ll arrive: There’s no need for minute-by-minute updates, but do tell your host when you’ll arrive. If it’s 35 minutes, say so, don’t gild the lily. And if you’re going to be more than a hour late, give your host permission to start without you. In fact, says Post, “ask the host if it’s better if you just don’t come”.

The host should be ready when they said the evening would begin: Post says one of the easiest mistakes hosts and hostesses make is that they’re not ready on time. “Let’s say you told people to arrive at seven. Chances are people will get there between 7 and 7:30, but you tell people to arrive at 7, and at 7, you’ve still got way too much stuff on the stovetop and you haven’t laid out the hors d’oeuvres or drinks.”

A guest should not bring a plus-one unless they’ve first cleared it with the host: “The good gracious host is going to welcome the uninvited guest in,” says Post. “They’re going to figure out how to rearrange the plates, add an extra place setting, and make it work. Make an uninvited guest feel just as comfortable.” But a good guest shouldn’t put them in that position.

The host should steer the conversation away from boring or sensitive topics:  A good host should politely interject with, “Sorry to interrupt, but I was wondering if I could get everyone’s opinion on X”, and, says Post, people will oblige. 

A good host should protect drunks from themselves – and other guests:  “Put them in a room and offer to keep them for the night. It’s really a safety issue,” says Post, adding that you are more or less taking on that responsibility when you serve alcohol in your house. “Take away their keys, say, ‘I’m insisting, you don’t have a choice, you’re staying here for the night. We will work it all out in the morning’.” 

A good guest thinks about what to bring: Avoid yet another second-rate, last-minute bottle of chardonnay or pinot. Post suggests something seasonal that may not be for the evening, like a jam or preserve or the perennial bouquet of flowers (already in a vase).

Put your phone away: Hide your phone for the better part of the evening and certainly while you’re at the table. Says Post: “As a host, it is live and let live, or you can specify on the invite itself, ‘I am dying to have a completely detached meal’, and say you can use them during cocktails, but not at dinner.”

If you’re new in town don’t shy away from any invitations. “And that is a time to definitely bring a gift for the hostess. Your best bet is flowers already in a vase,” Post says.

Offer to help out, but don’t insist: “You’re not this person’s best friend. Let yourself be a guest. Don’t try to insert yourself into everything.”

How to close down the night with grace: “Close down the bar,” says Post. “Once you cut people off from alcohol, they’re ready to go somewhere else or they’re ready to go home.” Or, you could talk in the past tense: “What a great night this was!”

Don’t forget your ‘thank you’: Says Post: “Say thank you when you leave, of course. And especially with people you’ve just started entertaining with, the absolute best thing is to send a written note the next day.” 

You can read more of Post’s tips at www.vanityfair.com.