'Lush textures in pale colours enhance the sumptuousness and warm you up by several more degrees than charcoal'
You know what's a practical, sensible buy in the sales? A white outfit. No, really. The key to making the January sales work is to restrict yourself to purchases that live in that section of the Venn diagram where two criteria intersect. First, you draw a circle containing those items that are sufficiently in step with coming trends that they won't feel like a waste of money and wardrobe space when you read your first "How to update your wardrobe for spring" feature. Next, draw another circle around those items you can wear now, because it will be winter for a long time, and trying to predict what you will want to wear in May is a mug's game.
There are no pink coats in the bit where these circles intersect, as no trend so closely associated with 2013 will survive long into 2014. Nor are there flimsy frocks – buy a summer dress now, and it will probably turn out to be the wrong one.
The trend that hits gold right now is winter white. White is going to be huge next season – I'm not just talking catwalk, it has been backed majorly by the high street, too – so it kicks your wardrobe into the future. And if you buy something warm, it will look springlike, but feel cosy enough to cheer up January. Lush textures in pale colours enhance the sumptuousness.
In The Goldfinch, Donna Tartt describes the pale-skinned, luminous Kitsey as "sugar-white". That sugar-cube brightness is how winter white should look. To achieve it – rather than ending up with a bleak paper flatness – you need to be smart about shade and texture. Off-white often looks brighter than printer-paper white, for some reason. (Obvious, but often-overlooked point: I'm not going to make you queue for the changing rooms, but please hold the fabric under your chin in front of a mirror.) Supple fabrics project sumptuousness better than cotton, which looks sad the moment it crumples, so textured sweaters and flippy, wool-mix skirts are better than white shirts, when the colour is the point.
Finally, the grubbiness issue. Do you know what? We're not six years old any more. Just avoid noodles for lunch. It's that simple.
• Jess wears jumper, £15, marksandspencer.com. Skirt, £59.99, zara.com. Heels, £290, stuartweitzman.com.
Stylist: Melanie Wilkinson. Hair and makeup: Laurence Close at Carol Hayes Management