Apply the Water Make-up into the hairline (do not forget the ears and the neck); this will prevent a mask-type effect.
Water Make-up dries quickly, so you need to work quickly to achieve a beautiful result. Don't work too dry, but do not use too much water.
If you do not want the colours to mix, be sure to wait for the first layer to dry before applying another colour over it or up against it.
When working with Water Make-up preferably use separate brushes for light and dark colours.