To mix food coloring properly, mix it in daylight to see the true color, adding less at first and adjusting carefully as you go. For lighter, paler colors, use liquid food coloring instead of liquid gel, gel-paste or powdered food coloring.
For deep, rich colors, use liquid gel food coloring in place of ordinary liquid food coloring, which gives the weakest color. For even deeper, more vivid colors, use gel paste food coloring. Be careful when mixing, as the paste is very concentrated and should only be used in small amounts. Powdered food coloring is also very concentrated and is commonly mixed by bakers with sugar to color cookies. When using food coloring for icing, the longer it sits, the stronger the resulting color.