20s: Katy Perry
"If you're a brunette with fair skin, reds with a blue undertone work best," says CoverGirl celebrity makeup artist Molly Stern.
20s: Sienna Miller
"Your lips are naturally fuller right now so you can get away with sheer, shiny textures," says makeup artist Emily Kate Warren.
20s: America Ferrera
"Burgundies and warm, brownish-reds look best on medium to dark complexions," says Stern.
For the most intense effect, apply your lipstick straight from the tube. "If necessary, you can use a lip brush to get the edges perfect," says Warren.
20s: Scarlett Johansson
Redheads can absolutely wear a striking lip color. "Choose an orange-based red to complement the warmth in your skin tone," says Stern.