To use this VENZEN hydrating pink foundation primer, first, make sure your face is clean and dry. Take a small amount of the primer and gently apply it evenly on your face, focusing on areas with large pores or where you tend to get oily. Let it dry for a few minutes before applying your regular makeup. When it comes to maintenance, keep the product in a cool and dry place, away from direct sunlight. Also, remember to close the lid tightly after each use to prevent it from drying out. Regarding the color difference and measurement issues mentioned in the description, don't be too worried. The slight color variation won't affect the product's performance, and the measurement differences are normal in the manufacturing process.