In a glass or plastic container, suitable for the size of jewelry to patina, squeeze a quarter size drop into the bottom of the container. Add water. And stir. It should be a strong yellow color. Drop your metal in and pull when it is black. Rinse in the baking soda/water solution to stop the patina process and neutralize the chemical.
More info when using liver of sulfur. Warm or hot water will cause a quicker and darker coloration on the metal. You can get this by boiling water in a kettle or using hot tap water. A coffee mug warmer works great to keep Liver of Sulfur warm if you going to be using it several times.