The secret to looking effortlessly stylish? A little work and a few simple rules | Jess Cartner-Morley on fashion

To be thought effortlessly stylish is the very best of compliments. A designer wardrobe can be bought; the bone-deep chic that enables you to sling a sweater over your white T-shirt just-so and look fabulous can not.

Effortlessness is the most prized of attributes, because it implies that style runs through your veins, rather than something you paid through the nose for on Bond Street. An effortlessly stylish aura looks like the outward manifestation of some inner fabulousness. And it is so much better to be thought effortlessly chic than cutting-edge fashionable.

It is a style that looks intelligent and grounded and sustainable, where trendiness looks flashy and flighty and bad for the planet. What’s more, effortlessness doesn’t have to be expensive, because it is often about having the confidence to play with the clothes you already own, rather than about buying new ones.

Effortlessness is sometimes conflated with timelessness, but it isn’t the same thing at all. When someone looks effortlessly chic, they look current, because while it is never about trends, it is very much about a subtle channelling of the zeitgeist. So, right now, it’s about draping your cardigan over your shoulders rather than tying it at your waist, about flipping an open shirt cuff back rather than rolling the sleeve to the elbow. It’s about knowing when to tuck a sweater in and when to leave it loose, and how many shirt buttons to undo.

None of which sounds like rocket science. But effortless chic, much like natural makeup, requires a little spadework behind the scenes. And that’s where it gets interesting. Don’t get me wrong, I can moon over old photographs of Jane Birkin till the cows come home, but I’d much rather dig into the styling tricks I can borrow from those old photos, and map them on to what I’m going to wear today.

Effortless style shows that your antennae are attuned to the world around you, but you are always yourself

The first rule of looking effortless is simplicity – which is different from minimalism. So, for instance, take the colours in your outfit. Minimalist might be all black, or top to toe white. Effortless might be jeans with a grey T-shirt and a navy blazer, or a checked shirt with plain trousers. The second rule is to choose understatement over statement. If you apply that to accessories, it will steer you away from a cowboy hat and towards, say, a ponytail tied with plain silk ribbon. The third rule is to bring a personal touch. So pick out your favourite name necklace or the discreet stud earrings you were given for a birthday rather than this week’s must-have.

Effortless style shows that your antennae are attuned to the world around you, but that you are always yourself. Your antennae have picked up Paul Mescal at Glastonbury knotting his spare sweatshirt cross-body, over one shoulder and under the other arm, and adjusted your own knitwear draping accordingly, without making a big deal of it. You know that a proper sock rather than a trainer liner is a modern non-negotiable. Add a battered varsity jacket you’ve had a decade, and a bracelet you love because you picked it up on holiday, and you have a recipe for charm.

Related: My trick to looking polished but staying comfy? Secret pyjamas | Jess Cartner-Morley on fashion

Sprezzatura is an Italian word that means lightness of spirit. Nonchalance, in other words. It first appears in a 16th-century etiquette guide by Baldassare Castiglione, aimed at arrivistes in the royal court, to describe the vibe one should aim for, of being witty and great company in a way which appears guileless and natural. Translated into an outfit, sprezzatura is effortlessness. It nails the level of smartness we are hoping to achieve, which I’d describe as relaxed flair: not polished, but not dull either. The ideal is to dazzle with the perfect level of dishevelment. Hair, for instance, should not be blown-out, but gently tousled. Imagine you have just got out of bed, but in a romcom rather than in real life, and you get the picture.

I forgot an important golden rule. Never, ever let on that any of this does not come as naturally as breathing, or the entire effect will be ruined. Effortless can mean different things. But easy isn’t one of them.

Stylist: Melanie Wilkinson. Stylist’s assistant: Sam Deaman. Hair and makeup: Sophie Higginson using Kiehl’s hair and Laura Mercier. Models: Naoko (left) from Grey Agency and Maria Diniz at Milk (right) . Naoko wears: Shirt, marksandspencer.com . Jumper, reiss.com . Trousers, from a selection, filippak.com . Earrings, pilgrim.net . Maria wears: Dress, from a selection, vince.com . Belt, zara.com . Earrings, pilgrim.net . Necklace, tillysveaas.co.uk