It’s one of those nights — Natalia Vodianova, the 22-year-old Russian model, and her husband, the aristocrat Justin Portman, are throwing a party at their apartment in New York. It’s friends, food — Vodianova’s home-made soup and chocolate eclairs — and family, including the couple’s son, Lucas. The theme is the 1920s and everyone is up for a bit of silliness. Look like fun? Well it was, and it perfectly captures all that’s good about this year’s party season: having fun with your nearest and dearest; letting go; ignoring what’s “cool”.

This cosy mood — let’s call it the Big Love-in — reigned at the recent Amfar ball in Venice, when Sienna Miller, Joseph Fiennes and Jeremy Irons, dressed to the nines, spent the evening sprawled on beanbags. It is also the prevailing spirit at dinner parties thrown this month by Damon Dash for friends including Jade Jagger, Kate Moss, Kevin Bacon and Mick Jones of the Clash. Held at his London home, they drank Dom Perignon, played pool and chewed the fat. They were low-key, but they were fun.

Big, starry, show-off parties are out, you see. The Big Love-in is all about a knees-up at home — decking it out, filling it with people who are worthy of your time, dressing up in ridiculous clothes and frolicking to Video Killed the Radio Star by the Buggles, because you like that song even if nobody else does. It’s the return of old-fashioned entertainment. Just don’t tell the cool crowd. They wouldn’t understand.

THE GOOD HOST

Let’s cut to the chase. Rule numero uno of being a decent host is: sharpen up with a couple of stiff ones before anyone arrives, then pace yourself. You need to set the tone for the evening, which means that, in the crucial early minutes, when the guests are nervous and shy, you must be in control, but not too in control. “The host is a human portal from the outside world into the magnificent inner world,” says David Piper of the Modern Times Club, who is one of the country’s most sought-after party organisers. “Like a kind of Black Rod, he or she coaxes out hidden personalities and brings them into the spirit of the party.”

A few hours later, when everyone has admired your ensemble and you’ve given each guest a moment of your time (or a conspiratorial wink, at the least), you may decide the party can look after itself. At this point, feel free to indulge yourself with shameless abandon. It’s your party, after all.

THE GUEST LIST

Invite your best friends. And your best friends’ best friends. The more eclectic the crowd, the better the party. Be inspired by the Duchess of York, spotted on the dancefloor at Elton John’s white tie and tiara ball with Posh Spice’s mum, Jackie, and with Kate Moss at Sketch a month later. A bunch of animated strangers is a surer guarantee of a good time than a clique of bored clones. “Eighty percent of a party’s success is the people who come,” says Piper. “You want people who are active within it, be that going around pinching bottoms or just being a witty conversationalist. Actually, I think it comes down to saying hello to other guests at first eye contact.” Be open-minded.

THE LOOK

Chuck out the rule book this year, because anything goes. Literally. A 1980s polka-dot cocktail dress with jeans and Converse trainers. A devastating floor-length sequined gown with a quiff. A man’s three-piece suit. A 1920s flapper dress. As the rules governing what we should wear at any given time evaporate — evening wear as daywear is now perfectly acceptable — the trend for party dressing is: whatever floats your boat.

“A good costume is an instant icebreaker,” says Thorunn Magnusdottir, from the Honeymoon, who makes people wear her favourite leopard-print catsuit if they’re feeling a bit stiff. “People look ridiculous in it,” she says, “and it breaks down their barriers.”

Fancy-dress parties, a winner for closet extroverts, are de rigueur right now (Style’s Wardrobe Mistress reports increasing interest from her correspondents). “But you have to be strict,” says Heidi Klum, whose annual Hallowe’en party is one of New York’s most jealously coveted tickets. “If you don’t wear a costume, it ruins everything. People have to go crazy with fantastic outfits. Putting on a clown nose and a hat isn’t enough.”

Perhaps the best way to break the rules is to create some new ones. Begin by banning 1970s, vicars and tarts, and anything that encourages 6ft beer monsters to wear lipstick. The aim is to fire the imagination, not murder it. Be clever instead. Get everyone to dress in a uniform, for example — after a few mulled wines, encountering a member of a Swat team in the loos can be beyond surreal. Or take a night off from “safe black” and make them wear brighter-than-bright colours. Or a mad hat (a less scary option than going for a full-blown costume). Or, since pure glamour is so now, darling, choose a book or era that particularly inspires. Kate Moss’s The Beautiful and Damned-themed 30th-birthday party was her sartorial gift to the pleasure-loving fashion crowd. Usher’s 1920s-themed party saw the hip-hop stars P Diddy and Jay-Z dress like bootleggers, watching their moll, Mariah Carey, do flapper moves. Now, that was a sight worth seeing.

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