Painting with washes is an awesome way to paint for people like me who are lazy
Undercoat the marines white, then use a pink/purple wash on the pink bits and a black wash on the black bits. You might need a couple of coats but you will get a really nice shading effect on the armour similar to the pink bits seen on the infantry models above.
Same with the black wash on the black armour parts, though watering down black paint might be more efficient as the
GW black wash isn't very strong.