When painting flower petals, leave a space for the center. Do not paint the color of the petals all the way to the center of the head of the flower and then add the center color either wet or dry. By doing this the colors will bleed into each other and it will not show up very well. Leave some of the white of the paper to fill in a pretty contrasting color for the center. This will allow the center of the flower to have a bit of it's own brilliance. It will also give the flower more depth and shape.