I had to change the shape of my own voice. It was quite hard to pull off and so once I had it, I stayed in Hitchcock's voice all day on set.
The best preparation for acting is life - observing life and people and observing yourself. All that becomes your library. So when you have to research a part, a scene or an emotion, you go into the library and get what you need.
I save her marked-up manuscripts as an unluckier husband might save love letters.