To use this QIBEST color - changing foundation, first clean and moisturize your face. Then, squeeze a small amount of the foundation onto your fingertips or a makeup sponge. Gently pat or spread it evenly across your face. When applying, you'll notice the color changing to a natural yellowish tone as it touches your skin. For best results, blend well around the edges of your face. As for maintenance, keep the foundation in a cool and dry place, away from direct sunlight. Make sure to tightly close the cap after each use to prevent it from drying out. Also, check the expiration date regularly. If you have sensitive skin, it's a good idea to do a patch test on your wrist before full application.