When selecting your color, choose from basic green food coloring or brighter neon versions available at most grocery stores. You can also mix yellow and blue coloring until you achieve the desired hue. You will only need a small amount (approximately 1/8 teaspoon) of coloring.
In a large bowl, mix the chosen color or color mixture with 2 1/2 cups of basic white vinegar. To achieve a vibrant hue, begin with 1/8 teaspoon of the coloring, or a ratio of 20 parts vinegar to one part coloring.
Continue adding food coloring to the vinegar mixture until the saturation is to your liking. Mix in yellow or blue to affect the hue. Yellow will lighten the green into more of a grassy shade, while blue will move the shade closer to teal.
Using a spoon or other instrument, mix the vinegar and coloring together. Do not use your fingers unless gloved, as food coloring will stain skin.