The shape, width and quality of the brush are to a great extent qualifying the effect you can achieve with it. For instance, round brushes are ideal for making curves and drawing curls. You draw straight lines preferably with a flat brush, keeping the handle of the brush pointed in the direction of the line. 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.