From Christopher Schink, in the September 1999 issue of The Artist’s Magazine:
To paint like James Abbott McNeill Whistler, group objects into simple silhouettes over the whole page, and avoid adding too many details. Use opaque pigments and a limited palette to create a feeling of weight and mood. But more quickly, since dry opaque pigments are difficult to work with. Focus on contrasts of intensity rather than differences of light and dark, to convey the effects of reduced light.