make-up as any other product expire. contamination could usually shorten the product's shelf life so it is important to handle your makeup properly so you can maximize the shelf life of your product. hygene is very important to prevent it from contamination as well as keep you from having separate sets of makeup that you use for yourself and other people. here are some points that you need to remember.

1. always sanitize your hands. use a hand sanitizer or alcohol prior to handling your or someone else's face.
2. always start with a clean, toned and moisturized face.
3. when using cream or liquid products, do not touch the product directly with your finger, brush or any other applicator that you use to apply the product on the skin. when you do this, you are directly exposing your product to germs and bacteria. what you should do is take a spatula, scoop a portion of the product and transfer it to your mixing plate or palette. make sure not to take too much product to avoid wastage. this also should apply to cream liners, lipsticks and gloss.
4. when using loose powder or pigmented shadows, you may also use a spatula and transfer it to a container before applying the product using your brush. pressed powders do not absorb much bacteria since its surface is dry and bacteria like damp or wet areas.
5. when using an eyeliner pencil or lip liner, ALWAYS sharpen the pencil before and after using it. sharpening it removes any germs or bacteria dwelling on the surface of the product. if your liner is strictly for personal use, then you may opt to sharpen it once a week.
6. don't pump the mascara wand and send in air in the tube that could contaminate the product. instead, as you draw the brush out, turn it slowly to scrape the product from the inside of the tube. throw away mascara after 3 months.
7. throw away liquid liners after 3 months. i recommend using gel liners as it has longer shelf life than liquid liners when using spatula.
8. store your makeup in the refrigerator. this also help you preserve its quality.
9. use disposable sponges instead of using the sponge included in your makeup package. if you are not comfortable using disposable ones, clean your sponge weekly and discard it after a month. DO NOT reuse sponge to more than 1 person.
10. always clean your brushes. make sure you clean your brushes after you use it. daily spot cleaning is recommended using a brush cleaner and weekly deep cleansing must be done using a mild baby shampoo.

here is a comparison of how long you can keep your makeup products when doing the tips above and when you use your make-up the usual way.