If you extend sharp lines, for example by extending the naso-labial fold line downwards, this will give a negative and even rather mean effect. The longer the line, the more severe the character will appear.
The teeth are painted over the lips using white Water Make-up.
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.
Hint: Regularly change the water you rinse your brushes in and preferably work with two water bowls: one for light and one for dark shades.