Hitchcock on ....

Dressing Eva Marie Saint for NORTH BY NORTHWEST:

Pearls of wisdom from Alfred:
"Suspense is like a woman. The more left to the imagination, the more the excitement. Audiences are more enjoyably scared when they think about rather than see mayhem.
The conventional big-bosomed blonde is not mysterious. 
Audiences like romance with their mystery. They always want to know "where does the girl fit in?"
Movie titles, like women, should be easy to remember without being familiar. 
The perfect "woman of mystery" is one who is blonde, subtle and Nordic, like Eva Marie Saint. How to achieve this mystery? By what she says, by the way she dresses, and by her actions. 

"I suggested she be dressed in a basic black suit (with a simple emerald pendant) to intimate her relationship with Mason; in a heavy silk black cocktail dress subtly imprinted with wine red flowers in scenes where she deceives Cary; in a charcoal brown, full-skirted jersey and burnt-orange burlap outfit in the scenes of action.

The intention was that she be dressed brightly while the mood of the scene was subdued - and quietly while the mood was exciting. A simple matter of contrasts. After all, she plays a woman of mystery - and no woman is a mystery unless she keeps people guessing."

From a 1959 interview in  "Films & Filming".

Well, we knew Hitch loved dressing up his leading ladies - Janet Leigh as Marion Crane had to make do with shop clothes a secretary would buy, but Hitch must have had a lot of fun dressing his new discovery Tippi Hedren for THE BIRDS (that famous green suit!) and MARNIE. He and Saint had a lot of fun creating the sleek look for Eve Kendall. Below: Eva dressed for the climax of NBNW in that fabulous house created for the film, right by Mount Rushmore!