To use this eyeliner and mascara set, first, hold the eyeliner close to your lash line and gently draw a thin line along it. For a more dramatic look, you can make the line a bit thicker. When using the mascara, start at the base of your lashes and wiggle the brush as you pull it up to the tips to separate and volumize your lashes. As for precautions, keep the products away from your eyes if you have any eye irritation or allergies. Don't share these products with others to avoid infections. To maintain the quality, store them in a cool, dry place and make sure to close the caps tightly after each use. Replace the products if they start to dry out or change in smell.