Using this BEN NYE MEDIAPRO HD Concealer Blue Neutralizer is easy. First, clean and dry the area of your skin where you want to use it. Then, take a small amount of the concealer on your fingertip or a makeup brush. Gently apply it to the blue or blue - green discoloration, like veins or bruises. Blend it well with your skin until the color is evenly covered. As for precautions, avoid getting it into your eyes. If it accidentally gets in, rinse thoroughly with water. To maintain its quality, keep it in a cool and dry place. Don't expose it to direct sunlight or high temperatures.