Tip #1: Store lipstick in the fridge. It will last weeks longer.
Tip #2: Never use a tester on your lips. It's just plain unhygienic. Instead, test lipstick on your fingertips. It's a closer fit to your lips than the back of your hand.
Tip #3: Use liner on your lips as a base. Lipstick will last longer if you fill in your lips with the liner first. If you're using light lipstick, try a nude liner.
Then slick your lipstick on top.
Tip #4: Don't skip the liner. Without the prerequisite liner, your lips will look "smudgier" according to Berg, softer & less defined....