Launching her book Elixir in Paris, Hilary Duff kept her look fresh, shimmery and accessible. One of the best ways to acheive a similar feel? A few swipes of iridescent white liner underneath the bottom lashes. It adds definition in the subtlest way, both opening the eyes and drawing attention to them without being vampy or overbearing. Just be sure to choose a sheer formula with a hint of sparkle—matte versions can look chalky.