Question: When should I be using lip liner and what's the best way to apply it?
Answer: Lip liner is to lipstick what primer is to foundation or a base coat is to nail polish—it's not crucial, but it does make your lipstick look better and last longer. Here's when to consider using one:
1) If you have thin or uneven lips. Outlining your lips with a pencil that's one shade darker than your natural lip color will make them look instantly fuller and defined. Avoid contouring outside the lines—"it only works on camera," says makeup artist Nick Barose—but you can build up your Cupid's bow ever so slightly and tap highlighter over for a plumping effect.
2) If your lipstick has a shiny finish or moisture-rich formula. Moisturizing, glossy lipsticks tend to bleed more than their matte counterparts. To keep the color from migrating, makeup artist Troy Surratt recommends using a natural, rose-toned pencil to line your lips, then dabbing concealer all around your mouth and setting it with loose finishing powder before applying lipstick.
3) If you want your lipstick to last all night without reapplication. For extra insurance against fading and to avoid a ring of color around the outside of your mouth at the end of the night, fill in your lips completely with pencil before appying your lipstick. The waxy consistency will act like tape to hold the color down longer.
4) In place of lipstick. Lip pencils are basically supercharged matte lipsticks. Choose a thicker one with a soft tip, like Nars Velvet Matte Lip Pencil, and use a smudge brush to blend it in.
Image courtesy of Harper's BAZAAR