Off-duty beauty: What models wear when they're away from the catwalk

As if it weren't enough that we envy models for their natural poise, ethereal good looks and the fact that it's their job to wear beautiful clothes, we're now envying their off-duty wardrobes, too. It's the new fashion conspiracy: the mannequins are taking over from their masters and creating a new wave of street style, which has in turn been emulated by designers themselves. Fashionstein's monster, if you will – the styled are becoming the stylists.

The first thing to learn about being an off-duty beauty is that you must never look as if you have tried too hard, or even tried at all. The look is effortless and thrown together – layering is key, so pick T-shirts, cardigans and jackets that can be worn as an ensemble or as separates. A graphic T-shirt is always fun, provided the graphic is cool – stay away from slogan tees or anything that proclaims what percentage angel/devil you are. Vintage rock T-shirts have been around for a while, but their star is still in the ascendant. Choose baggy ones that look a bit weathered, or weather a fresh one yourself by washing it excessively to fade the print.

Models tend to look gorgeously lost in oversized clothes. This is possibly a facet of their being very skinny, but oversized clothing is also a pleasantly luxurious aesthetic that means you can really snuggle into your winter knits and big scarves. Baggy cardigans should hang open and fall to mid-thigh. A skinny leather jacket should go over the top, so the length of it and your knit are a little mismatched (think dishevelled chic), or pick a mannish blazer with statement shoulders. The sleeves of this should be rolled up and the collar prominently popped.

Leggings are currently encasing the gazelle-like limbs of most models, hipsters and stylists' assistants – the choice between Lurex and plain cotton is yours, but lamé has a habit of sticking to whatever you sit on and creaking when you cross your legs. For the more timid, a pair of narrow black jeans is more than acceptable, especially when paired with biker boots. Theoretically, the clumpier your footwear, the skinnier your legs look, but if you want to remain chic, then slim, over-the-knee boots are a good alternative. Models are also into their bandals right now (half-boot, half-sandal – keep up), which can sharpen up this casual style, while providing a suitably hip amount of toe cleavage.

Your finishing touches should be a knitted hat (it can get cold backstage), a loosely knotted scarf and a superb bag. Most models are "gifted" this season's must-have handbags by the designer, but if your friends or colleagues aren't as generous, look for one that is slouchy and slightly too big. Remember, it'll make your shoulders look thinner.

Fashion's revolving door: What's in and out this week

In – Over-the-knee boots

As seen on the catwalk at Gucci and Halston, OTKs are simply the best thing to happen to autumn/winter. Freeing us from the bulky-calf tyranny of the slouch boot, and the chilly-knee territory of anklers, they can suggest dressed-down folk or uptown chic. Those extra two inches of leather or suede also allows for the wearing of short skirts, and the tucking in of jeans. Over the knee boots: Russell & Bromley, £275

Out – Over-the-knee socks

The idea is so nice: in plain colours, they're cute and preppy, but also tantalising. In reality, they suit no one but Japanese schoolgirls. And they don't stay up. If you happen to be one of the minority who can work the sock trend, don't despair – Marni showed on the knees for spring, so you'll again have the pleasure of them slipping round your ankles.

Harriet Walker