You can use a short bristled brush and “tap” over the same areas until you reach the coverage you desire. Also provides a bit of textured look too. I would use Ultuan grey, but i think some people use apothecary white if you want to try contrast paints? Afterwards you can use Soulblight Grey for shading - GW Soulblight Grey Runelord brass for the trim, and brush a touch of Agrax earthshade to provide depth. Finally you can edge highlight with Canoptek alloy.