Lily Collins' sleek half-updo at the premiere of The Mortal Instrument is the exact look we're craving right now—fall always calls for more polish. We caught up with her stylist, Mara Roszak and got the play-by-play on how she created the look. “Lily wore an incredible leather, structured dress by Cushnie et Ochs. I knew I wanted the hair to have a graphic feel with lots of shine," Roszak told us. She started by sectioning her hair deep to the side and then applied Leonor Greyl Mousse au Lotus Volumatrice ($46 at leonorgreyl-usa.com) to Lily’s damp hair and blow-dried it straight. "For an extra sleek look, I flat ironed each section straight down with no bend," said Roszak. She used Leonor Greyl Gel a l’Hibiscus ($35 at leonorgreyl-usa.com) to slick back the sides of the hair and pinned it in the back, leaving the back section down. As a final step to ensure staying power, Roszak misted hair spray all over the head. We especially love the makeup details like sexy, oxblood lips and Collins' signature bold brows. Bring on fall!