Tint dough a little darker than you would tint icing; cookies will bake lighter than dough appears. After dough is mixed, take out the portion to be tinted. Add just a little color with a toothpick. Gently blend color into dough using stand mixer paddle attachment, or knead in by hand. Stop to check the color. If it is too light, add a little more color and continue mixing until desired shade is reached.