The best way to keep warm is through stylish layering. The operative word being stylish, meaning you don't just pile pieces of clothing on top of each other. Fit is key to achieving the layered style, so attempt this only with clothes that fit your body well.
You can achieve this same effect by wearing a shawl collar cardigan and shirt combo under this Boss Black window-pane jacket (below left, HK$6,800) and pairing it with dark brown corduroy trousers. Add a Burberry Prorsum field jacket with military details (below right, HK$20,500) and accessorise with a cashmere fedora from Ermenegildo Zegna (above right, HK$2,850) to balance formal with casual.