Tint a small ball of cookie dough. The important thing is to add just a little of the concentrated icing color at a time, until you arrive at the exact shade you want.
Roll dough into a ball, kneading until it's soft and pliable. Using a toothpick, add dots of icing color and/or flavor in several spots.
Knead color into your dough ball; be sure to wear All-Purpose Decorating Gloves to keep your hands stain-free.
Continue kneading until color is evenly blended; add a little more color if needed.