Imperial German Cavalry for Return of the Tripods. These are the colors I happen to have on hand and others may work just as well. This scheme uses block colors with no real shading so it has sufficient contrast at a 15mm scale.
Prime in white and then paint the saddle blanket   Caledor Sky  
Paint the uniform   Field Blue  
Heavy drybrush the uniform with   Fenrisian Grey  
Paint the gas mask, straps, and pouches of the soldier and the gas mask on the horse   Sandstorm  
Paint the horse   Doombull Brown  
Paint the saddle straps, and the horse’s mane, tail, and hooves    Corvus Black  Paint the soldier’s boots and dot his eyes.
Paint the lance, rifle, and holster a lighter shade of brown with   Mournfang Brown  
Paint the explosive lance tip in   Khorne Red  
Paint the hands in   Cadian Fleshtone  and wash with   Flesh Wash  
Give the horses white socks with   Bold Titanium White  and paint the stirrups in   Leadbelcher  washed with   Dark Tone 
Paint the gas mask filters in   Eshin Grey  
Paint the base to match your basing material   Warboss Green