Born in Jacksonville, Illinois, and later moved to Bloomington, Illinois. After graduating from high school in nearby Normal, Best moved to Los Angeles to attend the Chouinard Art Institute. Her first job as a designer was with the Western Costume Company, circa 1926, followed in the 1930s by United Costumers, Inc. In 1947, after Warner Bros. bought out United Costumers, she was offered a job in the wardrobe department and went on to become one of the studio's top costume designers, specializing in men's costumes and period films.

Costume Design (Black & White) 1949: ADVENTURES OF DON JUAN (w. Leah Rhodes & Travilla)  Nominated for Costume Design (Color) 1956: GIANT (w. Moss Mabry)  Nominated for Costume Design (Color) 1960: SUNRISE AT CAMPOBELLO  Nominated for Costume Design (Color) 1965: THE GREATEST STORY EVER TOLD (w. Vittorio Nino Novarese) 4 nominations, 1 Award