Layering doesn't just keep you warm - done right, it can elevate your outfit into a "look" | Jess CartnerMorley

Are you tri coat? Believe me, you must be. It's not just a trend - it's a life hack. Three-way layering is a brilliant formula for winter dressing. Three layers are warmer than two and more comfortable than one. It's cozy but civilized. It has style without being frenetic.

Wearing three layers instead of two elevates an ordinary outfit to a "look". A shirt under a blazer is commonplace; a knitted shirt and V-neck under a blazer is preppy chic. A long-sleeved T-shirt under an open shirt (jacket-shirt, come on) is ok; add a fine knit polo neck under the t-shirt and jacket, on the other hand, and suddenly you're dressed for a romantic encounter with hot chocolate.

The tri-layer has been with us for years, in a discreet way. But while a thermal vest tucked under your shirt and sweater is technically three-layered, it doesn't count as a fashion move. All three elements of your look should be visible, and the trick to making this work is to make one of the three sleeveless. Three sleeves is too bulky and gives you weird, scarecrow-like lumpy elbows. It's not comfortable - ugh, just thinking about that stuffed sausage feeling makes me grumpy - and the diapers can't slide on top of each other.

It's your torso that really matters when it comes to staying warm, so it makes sense to have one more layer there than on your limbs. For three to add up, so to speak, the colors have to work. Stick to classic contrasts (red, white and blue always work) or opt for neutral tones with, for example, three pale neutrals.

The best options for the sleeveless layer are a knit tank top or a quilted vest. In other words, either an armless sweater or an armless puffer jacket. The quilted vest works for streetwear and dressy wardrobes; a knit cardigan is perfect if you tend to wear suits and dresses.

A tank top is a great third wheel, and there are some cute Fair Isle styles on Etsy . The neckline depends on what's going on underneath. A V-neck is best if you like to wear a blouse or shirt with pants under a blazer. If you're more into t-shirts, opt for a crew neck that you can wear over a long-sleeved t-shirt.

The sleeveless knit between also in play its own with these light, loose, probably printed dresses with long and perhaps puffy sleeves that we have all worn a lot in the last two summers. I tried wearing chunky sweaters over mine, thinking it would look romantic - like maybe I was going for an emotional walk - but it looked like I was wearing something over my nightgown to take out the trash. A sleeveless knit shows the sleeves and brings the dress back to being a dress, so it looks elegant again.

A quilted vest is for more streetwear types – and Weekday has some good affordable versions. A sleeveless quilted jacket might look a bit "basic" worn just over, say, a sweater - a touch of 1980s mail order if you know what I mean. But they are a joy to wear, putting a spring in your step by being comfortable without being heavy, and as one of three layers they are ideal. Start with a knit polo neck, add a denim or khaki overshirt, then pull the vest over it. Or layer a T-shirt under a contrast half-zip, then add the vest.

See? Just like that, you're transported from the Littlewoods catalog to a J Crew shoot, maybe in Brooklyn. I told you three was the magic number.

Model: Eliana at Body London. Hair and makeup: Sophie Higginson using Davines and Rose Inc. Blazer: next.co.uk. Shirt and sweater: meandem.com. Pants: yaitte.com