The Cubists introduced text, usually in the form of newsprint, into their still life works, giving them a look suggestive of graphic design .
Don't be afraid to use blacks and browns in a still life painting, but make them interesting. An all neutral painting will need a feature note of red or some other warm colour somewhere to give it life.
This was often provided by the vermillion stamp in Chinese paintings.
Juan Gris, Still Life in Front of the Window.