Summarize this article:

Prepare at least four custard dishes or small bowls. Spoon about 1/4 cup (60 ml) of prepared white frosting into each dish.  There are multiple ways to create orange frosting, but each one requires a base of white frosting. You'll need at least four samples of white frosting, but setting up six to twelve will allow you to experiment with more options. You should obtain at least four different food dyes: one orange, one red, one yellow, and one black. Consider getting additional hues of red and yellow for additional experiments. Ideally, you should use paste, powder, or gel food dyes that are designed for use with frosting. Avoid liquid food dyes since these tend to have a negative effect on frosting consistency. Dunk separate, clean toothpicks into one container of red food coloring and one container of yellow food coloring. Mix both dyes into another sample of white frosting, continuing until no streaks remain. The combination should result in an orange frosting. This second sample may not look exactly the same as your first, of course, since the red and yellow you use may result in a slightly different hue. Create another sample of orange frosting using the orange food dye or the combined red and yellow dyes. Mix a very small dot of black food coloring into the sample, as well. The black should darken the shade of the orange without changing the hue. Only use small amounts of black food coloring at a time, though, since even small amounts can have a dramatic impact on the color of the frosting. If you prepared any additional samples of white icing, you can use them to experiment with different combinations or food colorings. Take notes so you'll be able to duplicate the same orange hues and values later.  Most food coloring manufacturers have recommendations for you to follow, but you can easily experiment on your own. Several ideas include:  Combine nine parts red with ten parts yellow to create a rosy peach color.  Mix two parts orange with one part golden yellow to make an apricot color.  Create a rusty orange by mixing eight parts orange, two parts red, and one part brown.

Summary:
Set up a few samples. Combine red and yellow food coloring in another sample. Create a darker shade of orange. Try other combinations as desired.