As reported by Lily William, The Bulletin:
He appeared in the pilot for "The Beverly Hillbillies," but turned down an ongoing role on the series because it sounded too silly to him to be successful. He became a contract player for Desilu, where Lucille Ball was impressed enough with Osborne's breadth of film knowledge, especially about character actors, to make him one of her inner circle.
The real turning point in Osborne's Hollywood career, however, came when Ball (who was something of a mentor to him) advised Osborne to forgo acting in favor of writing. "We've got enough actors," she said. "Write a book. It doesn't even have to be good. Just having a published book will bring you respect in the field."
Following Ball's advice, Osborne wrote Academy Awards Illustrated, today considered by many to be the bible of Oscar histories.