What should I wear?

The worst fashion faux pas I've made was turning up to last year's Westpac Red Collection dinner - widely regarded as Fashion Week's most glamorous night - in a pair of jeans. Everyone else wore a glittering cocktail frock or long gown. Luckily I'd thrown on a sequinned and be-mirrored Trelise Cooper silver coat, which blinded everyone from the telltale denim on my lower half and, no doubt, saved me from utter fashion shame.

But the event did highlight the minefield that dressing for special occasions often is these days. While men simply don a suit (dinner or regular), women have to grapple with an endless array of dilemmas. Long or short? Glitzy or plain? Flirty or demure? Black or bright? How can dressing up be so complicated?

You can lay the blame squarely on the studied casualness of our era, not to mention our laidback Kiwi attitude to pomp and ceremony. When almost anything goes and the notion of prescribed rules of dress feels somewhat antiquated, there's little wonder many of us are thoroughly bewildered by the unspoken codes that apply at 21st century social occasions.

But never fear. Help is at hand. We've grilled three experts and can advise categorically what you should be wearing where this season.

Fashion designer Yvonne Bennetti says that black tie means after-6 wear. This could be a cocktail frock or an evening gown - either tea-length (mid-calf) or ballerina (to the ankle).

Floor-length gowns are best reserved for much more formal affairs such as white-tie events and balls, for which dresses in hues such as silver, gold, "a pink we call coconut ice", canary yellow and orange are in hot demand.

"Sorbet colours, that look great accessorised with a diamond brooch, necklace or belt, are really big for next summer," Bennetti says. "The definition of cocktail is 5cm above the knee and it sums up the 'little black dress'. It could be fully beaded or fully sequinned," says Bennetti. "You can accessorise a cocktail dress quite stunningly. For example, you might wear an LBD with chandelier earrings and sky-high heels."

And what should we wear to the opera?

"One theory is that it's dictated by the price of your seat. If you're got a really expensive seat then, generally speaking, people are a little more dressed up. You might wear a cocktail dress - but it wouldn't be too shiny - or you might wear a tuxedo suit." Bennetti adds that it's considered good manners to dress up for an opening night and advises against towering Marge Simpson-esque up-dos that may impede the view of those seated behind you.

TVNZ style director Michiko Hughes dresses the network's celebrities - Pippa Wetzell, Wendy Petrie, Alison Mau, Bernadine Oliver-Kerby and Miriama Kamo - for red-carpet events such as the Qantas Media Awards.

"It's super-glam, just like the Oscars really," says Hughes. "The new look is very sophisticated. It's quite old-school feeling, very conservative ... just flowing kinds of gowns."

She looks to stars at the Golden Globes and Screen Actors Guild awards for direction. Of the moment are clean lines, "industrial-style" construction such as boning, sheath-like dresses, nude tones and "shoulder action".

Hughes advocates being measured in how much skin is shown.

A short dress with long sleeves, as Miley Cyrus wore to the recent Grammys, is a winner. So, too, is the backless gown with a high neckline that Kate Hudson wore to the SAGs.

"There's always a bit of mystery. You don't want to be showing everything off or you just look completely cheap and nasty."

Cocktail dresses may be either short or to the knee.

"It can be a little more flirty and fun. You can have some strong colours and printed fabrics," Hughes says.

When attending an edgier event such as the music awards, "you can wear shorter. It's rock 'n' roll, You can be quite 'out there'. If you've got it, flaunt it." Hughes has noted a big focus on statement jewellery, especially necklaces and jewelled cuffs in gold and diamantes.

As co-owner of fashion boutique Muse, Madeline Healy's confidential client list includes the wives of business leaders and high-powered politicians.

"For black tie you can wear long or short, depending on the formality of the occasion. This season I'd advise someone to wear a jewel-toned dress to stand out among all the back-clad men."

Colours she sees coming through strongly include citrus pink, purple, emerald green and cobalt blue.

Healy says that the trend is for cocktail frocks to be extremely short.

"So it's long on legs and short on hemlines. There's a lot of gold, bronze and molten metallics." Wearing skinny satin pants beneath a shift-style dress is an up-to-date option for those who find the high hemlines daunting. Healy recommends New York-based Kiwi designer Rebecca Taylor for "fantastic" beaded cocktail dresses.

"Comfort, no-crease fabrics and layering" are Healy's tips for a night at the ballet, the theatre or the opera.

"A cocktail dress is often worn but for a "more directional look" she suggests an embellished top, a boyfriend jacket - perhaps the Olsen twins' Elizabeth and James label - with the sleeves pushed up, slouchy satin pants that taper at the ankle and high-heeled shoes.