Pour the yellow dye into a clear glass bowl. Pour in your water now if you are using food coloring dye. The exact amount of yellow food coloring is going to vary depending on what you are coloring and how large of a mixture it is, but you want to make sure the object is bright yellow (not murky). The more yellow you add, the brighter the color.
Mix the yellow with a spoon so the the dye is thoroughly dissolved.
Add one drip of green dye to the yellow dye. It is important to mix the green after the yellow, because the darker color quickly takes over the brighter color. Wait for the one drop of green dye to dissolve before adding more.
Add one drop of green at a time. Mix it into the yellow and see if it is the exact lime green you want. Continue this process until you have the shade of lime green you are looking for.