Beauty Weekend Hair Idea: Rachel Bilson's Braided Half-Updo By Marianne Mychaskiw Marianne Mychaskiw Instagram Marianne Mychaskiw is a New York-based freelance writer and editor who covers everything from beauty and style, to wellness and entertainment. InStyle's editorial guidelines Published on July 27, 2013 @ 08:00AM Pin Share Tweet Email Photo: Alberto E. Rodriguez/Getty; Steve Granitz/WireImage Rachel Bilson hit the red carpet at the Los Angeles premiere of The To-Do List wearing a braided half-up style, but we think the look works just as well for more casual affairs. Plus, unlike a sleek blowout, this style looks even better once summer's humid elements come into play. "Rachel's dress was very polished, so I wanted her hair to look undone with an edge," said her hairstylist Davy Newkirk. To bring out the star's natural wave, Newkirk applied the Davines Volume Boosting Mousse ($26; davines.com for locations) before blowing out her strands with a boar bristle brush. He added extra movement by loosely wrapping sections around a curling iron, then misted on Bumble and Bumble's Surf Spray ($25; bumbleandbumble.com) to impart a lived-in finish. Once a precise center part was formed, he twisted the top sections on either side of Bilson's head into two separate plaits. "I braided them, coming together in the center, then pinned the braids under the back section of hair," he said. "Finally, I pulled the side sections of hair back, and secured them underneath to give the illusion of a ponytail." A veil of Oribe Superfine Hairspray ($29; oribe.com) kept the style in place all night. See more of the summer's sexiest hairstyles. MORE:• Rachel Bilson’s Beauty Look at The To Do List Premiere• Heat Wave-Induced Haircuts: All the Details• See Rachel Bilson's Hair -- On You!