Mise-en-scene while filming. How do I do that?

Basically my two roles are camera operating and sorting out the mise-en-scene. Camera operator is pretty simple, I'm doing what it says in the name. But mise-en-scene seems slightly more confusing. But to make sure that I do my job right I have done some research on it. Basically, I will be making sure everything in the shot is okay. If something is out of place then I will sort that out. It stands for 'placing on stage' Mise-en-scene consists of everything in the shot, lighting, props, clothing etc. Obviously as Melissa is doing lighting I will work fairly closely with her on that one.