One example of mise-en-scene in A New Hope is the setting. Of course, there is not only one setting, but some of the most memorable settings are the Cantina, and Luke and the twin suns. The cantina is messy, crowded, loud, and dark. This establishes the idea that it's a sort of "shady", or dangerous place to be. In the twin suns scene, there is a serene, beautiful setting while Luke overlooks the sunset, reflecting on his idea to leave the farm.
The lighting throughout the movie also plays a huge role. Referring to the cantina scene again, the lighting would be considered low-key lighting. The frame is cast with large shadows, and it's hard to distinguish many details. However, when the alien's hand it cut off after he harasses Luke, the lighting gets noticeably brighter, but returns back to dark immediately after, showing almost a climax of the scene, then the dying back down.
The costumes in Star Wars don't have the same effect on the movie as they do in most. In most movies, costumes set the time period. Here in star wars, they convey many thins such as economic status, good or evil, or personality. For example, darth vader wears all black and a mask. The fact that he is covered from head to toe completely gives off a mysterious vibe, seeing as the audience does not know what lies beneath the mask, and the black shows evil, in contrast to the white and tan colors that Luke Skywalker wears. Also the use of red and blue lightsabers (as seen in the fight scene between Darth Vader and Obi Wan) represent good (blue) and evil (red).
The spacing in Star Wars: A New Hope can be noticed in the fight between Obi-Wan and Darth Vader. When the scene begins, Obi-Wan enters a room, and his facial expression changes from slightly calm to concerned. However, you don't see what he's looking at until a few seconds afterwards. This is an example of offscreen space.