When you get down to the smaller scales, it can become quite difficult to hold onto a figure and paint it at the same time. In N scale, especially, trying to hand-hold a figure while painting it will often end up with painted fingers instead of figures. The solution to this problem is a simple one. Paint the figures while they're still attached to the sprue; then after you cut them from the sprue, a quick drop of paint at the connection point finishes the project.