This is the one paint I simply could not do without! It is a tube of artists' acrylic raw umber. Liquitex is by far the best and they have just come out with a new 'transparent' version which is even better than the original. I use it as a very thin wash which I apply to the entire figure once painted. It really brings the figure to life with a slightly weathered look which blends the colours and brings out the detail without the need to do any outlining. You can buy it in most artist supply shops.
I put a small amount on the palette, thin it down with a lot of water and wash it over the figures with a large soft brush. The wash should be very thinned down - little more than a puddle of muddy looking water.
I have now taken to applying a wash immediately before painting as well. I picked up the idea when I started painting 6 mm figures as it was hard to make out the detail with only the white undercoat in that scale. The raw umber wash picked out the detail and made it easy to block in the colours. It also provided a darker outline where the wash had settled into the grooves.
The raw umber wash has been applied to the figures after undercoating with white. You can see from the pool at the base of the female camp follower just how thin it is. You can also see how the detail has been picked up. You need to let it dry thoroughly before starting to paint