When you don’t have an idea, maybe you should ask around and see if anybody else has one. But don’t spend all day jawing with other creative people. Start with the producers. They know filmmakers, talent and music.
Art buyers may know a photographer or illustrator with a great idea and no place to sell it. What about content managers or digital strategists? Social? PR?
Sometimes, the idea has already been had. Your job is simply to find it and present it. And make sure you include your source in the credits.
You might need them again on your next project.