Mise en scene is a french word for ‘placing on stage’. Frame and camera work is important in Mise en scene. Usually a director needs to all of its elements like lighting, custom, location. In pre-production, director will discuss with his AD, set designers, prop masters, costume designers and scenic artists to determine the final look and feel the movie will achieve, the entire mood of the movie. More information and examples on here.

Montage is a kind of editing style. It cut a series of different scenes together to create time and space in film. Usually it is made up by the most important part, the most impactive part of the scenes. It would be New York this second, then next second it would be Paris, this kind of space and time differences will make audience excited and wonder. A montage cannot be two long or too short, too long would make it look boring, too short would make audience not satisfied by it.

Découpage, before we shoot a scene, we need to think about editing earlier before or during shooting. What kind of shoots are needed in later editing needs to be considered earlier. If we think it when cutting, it is too late. Sometimes we need a special angle, or special size of shot to get a better editing later, so think it earlier! ‘Almost universally confused in English-language writing on film with editing—when it isn’t completely ignored—découpage articulated instead an understanding by French critics that sequencing was conceived before and during the shooting of a film, not in the cutting, and that the camera played not merely a pictorial role but instead structured the film through its formal treatment and sequencing of the mise en scène’.

Reference:

http://www.elementsofcinema.com/directing/mise-en-scene.html

https://www.caboosebooks.net/montage-decoupage-mise-en-scene