Suspense I think the best example of suspense in Alfred Hitchcock's films is Psycho. The suspense is built well through the music and the camera angles. I will choose the shower-stabbing scene to demonstrate all these elements, because the scene displays all these elements the best. The music fits the situations and events that take place. The playing of the screeching music when Norman Bates is in the process of stabbing Lila Crane in the shower, just the effect of the music makes this one of the most suspenseful scenes in movies history, at least in my opinion. Also, the camera angle builds the suspense. The angle of her screaming when the man opens the shower, then the cutting off to the knife and then the blood, displays the effects of the camera angles, and without even show the murder. The angle on the knife makes us perceive that she is being stabbed without even seeing it.
And the blood makes us assume that she is dead, without even showing the body. He builds suspense without showing the specific details of a scene.
Plot Twists Hitchcock uses plot twists in his films to give the viewers the idea that something going on is happening, but in reality, it's not. For example, in Psycho, Norman Bates' mother really turners out to be Bates himself. And for Dial M for Murder, the key that was left on the stairs was used to help the detective catch Tony. The Trouble with Harry is that the whole time Harry has died of a heart attack, but we didn't know that and all the other characters didn't either. In Rope there really isn't one. You could say that the two brothers killing David and putting him in that box could be a plot twist.