Hi Murdo,
Instead of black for shading on these light coloured clothes try using a dark brown. Applied in thin washes to build up the colour and only use black for the very deepest shadows. I would also invest in some Vallejo Model Colour or Model Air for figures.
Paul
For cobbled roads, buy a pack of polystyrene bbq plates.( Poundshop ) Cut out the flat centres and gently scribe with a pen or similar. Paint with acrylic base coat,acrylic varnish then enamel washes etc
Also can be used for brickwork sections on walls. The sooty deposit left from burning a candle close to a flat shiny surface can be used as soot on your burnt out sherman as can the ash from cigarettes
Paul