A camel coat is the one piece of outerwear I think everyone should own before anything else. It goes over black, grey, cream, denim and brown, it makes a plain outfit look expensive, and it looks better than any other colour on a grey day.

The details that matter are length, shoulder and shade. I prefer a coat that ends somewhere around mid-calf, because it covers a skirt or a wide trouser without swallowing you. A soft, slightly dropped shoulder lets a thick knit fit underneath. And the shade should lean warm, closer to caramel than beige, so it does not wash out next to your face.

Max Mara's Manuela wrap coat, at $3,450, is the classic belted version for good reason. Nili Lotan's Adrien, in a glen tan check at $1,790, is the most affordable here, and Zimmermann's Valiant at $1,950 comes with its own scarf. At the top end, Loro Piana's cashmere coat is $9,600.

Belted or buttoned is personal. A wrap with a belt looks softer and suits a waist, while a straight, buttoned coat looks cleaner over trousers. Balenciaga's long coat at $3,950 and Valentino's at $5,300 are the sharper, buttoned options, and Max Mara's double breasted Madame is $4,490.

Under camel, I keep to a short list of colours: cream, grey, black and more camel. Cream is the softest, like Nili Lotan's Tomaso cashmere sweater in ivory at $1,090. Camel on camel, with Khaite's Jackson sweater at $1,580, looks rich without trying. Grey is the most practical, and Nili Lotan's Nora in medium grey is $740.

A black knit is my favourite, because the contrast makes the coat look sharper. Khaite's Leta in black is $1,340, and St. Agni's crew neck in taupe melange, at $429, sits somewhere in between.

For trousers, black is the simplest answer. Nili Lotan's cropped Corette at $650 shows a little ankle, which I like with a loafer. Khaite's Kaia at $1,680 and Grenare at $1,380 are longer and fuller, so they fill out the space under a big coat.

Denim works too. A straight blue jean with a cream knit under camel is my weekend version, and it looks just as good as the tailored one.

Brown shoes and a brown bag finish a camel coat better than black does, in my opinion. Black is fine, but brown keeps the whole outfit in the same warm family, and it looks more relaxed.

Loafers are my first choice. Khaite's Miles loafer in vintage brown leather is $1,080, and St. Agni has two cheaper options: the Suede Minimal Flat Loafer in coffee at $429 and the woven Bunto in chocolate at $329. For wet days, By Far's Este ankle boot at $490 or Khaite's slouchy Clive boot in dark brown at $1,680 both work under a long hem.

For the bag, a soft tote suits a coat this size. Mansur Gavriel's Everyday Soft Tote in chocolate suede is $895 and Khaite's Small Lotus Tote in dark brown suede is $2,900. By Far's Mini Longa in brown croc-embossed leather, at $490, is the small one for evenings.

If you do want black, keep it to one piece, like the bag, so the coat stays the warmest thing in the outfit.