Popular colors are yellow and pink, however you may use whatever colors you wish. I prefer gel colorings and I use a toothpick to scoop up just a bit of color and place it on the dough. If you are using liquid drops, start with 2-3 drops and add more as needed. After you add the coloring, knead it between your hands until the color is mixed in. The topping will be very soft and slightly crumbly.