Oyelowo recently appeared in a production of Othello opposite Daniel Craig in New York — he confesses that he has no secret tips to learning an entire play’s worth of dialogue. He explains, “I wish I did have a trick to memorize lines. I often fantasize about having a photographic memory. Unfortunately for me the only thing that works is hours and hours of saying them over and over and over again.”
Nonetheless, Oyelowo does credit his theater training for making him a more effective actor on screen, pointing out, “I think stage is the best possible preparation for being on-camera because if you know what it feels like to say great dialogue to actual people night after night you can make most dialogue feel truthful while being around cameras and the artificial environment of a film set.“
(via)