Most long wool or cashmere coats respond best to occasional professional dry cleaning rather than frequent washing. Between wears, hang your coat on a sturdy, broad hanger to preserve the shoulders and brush the surface with a fabric brush to remove lint. Spot-clean minor marks with a damp cloth and avoid overloading pockets, which can distort the shape. Store it in a breathable garment bag off-season to protect the fabric while allowing it to air.