First ask, who drives the scene, motivates it, and makes it happen? Any character or force might drive a scene, even an inanimate object or act of nature. Then look into both the text and subtext of this character or force, and ask: What does he (or it) want? Desire is always the key. Phrase this desire (or in the actor’s idiom: scene objective) as an infinitive: such as, “to do this…” or “to get that…”