Begin with white icing and concentrated icing colors. The concentrated icing colors will not affect your icing consistency. Ordinary liquid food coloring can thin your icing and affect your ability to pipe certain decorations.
Dip a toothpick into the color, then swirl it into the icing. Add color a little at a time until you achieve the shade you desire. Always use a new toothpick each time you add color to avoid getting icing in your color jar.
Note: If you are tinting your icing dark brown or black, begin with chocolate icing - your icing will not have the aftertaste that large amounts of icing color can produce. If you are tinting a large area of red, use No-Taste Red.
Blend icing well with spatula.
Note: Always mix enough of each icing color to complete your entire cake. For example, if you are going to decorate a cake with pink flowers and borders, color enough icing for both. It is difficult to duplicate an exact shade of any color and you will want to keep you colors consistent on your cake. Icing colors will intensify or darken in buttercream icing about 1-2 hours after mixing. Royal icing requires more color than buttercream icing to achieve the same color intensity.