It's not as if piling on outerwear is new (throwing a puffer vest over a denim jacket is as prevalent now as it was when Michael J. Fox did it in Back to the Future), but playing with proportion and the pieces you layer is.
Think of your go-to cold-weather basics (a peacoat, a leather jacket, a topcoat) as you would a shawl-collar sweater and a T-shirt. The rules are the same: Start with the most fitted item and add on from there. A moto jacket under a boxier peacoat works. So does a down vest over a topcoat, as pictured here—the hem should hit at the thigh to keep the balance right. Forget the conventional wisdom that the coat on the inside has to be shorter—it doesn't. Either way, you can get bundled up without looking like it.
From Left: Vest ($1,288) by Kolor, Coat ($880) by Ami, Shirt ($420) by Louis Vuitton, Jeans ($200) by Acne Studios, Shoes ($110) by Nike. Coat ($215) by Tallia, Jacket ($3,000) by Louis Vuitton, Shirt ($335) by Simon Miller, Pants ($1,090) by Jil Sander, Shoes ($410) by Common Projects.
—The Details editors.