I've been assigned to help with a short documentary in roles I don't have much experience in. Any advice?

I've recently been asked to help with a short documentary made by some people I know. The things they've assigned to me Include Lighting, one of the cameras, and being one of the sound people. It's a small crew so a lot of people are doing multiple things. I don't really have a ton of exposure to what being on an amateur film set is like, nor am I particularly super Familiar with Lighting and Camera work. Any advice on how to approach this or what it might be like when I get there? You don't have to tell me how to shoot or light a scene, just what might be expected from doing this project.