From the basics of composition and storytelling to the costs of realizing your dream, how to make a movie is a question that newbies and long-time movie veterans struggle with when they begin a new project.
I've shot video of a variety of subjects on an uncountable number of locations, and while I don't always take every light I have with me, there's one lighting tool that never leaves my road kit. As you're planning a shoot, remember that before you add artificial light to a setup, you should always see what you can do with the natural light you have.
Many would-be documentarians get trapped into thinking that only sweeping, epic topics are acceptable fodder for documentaries. They just get stuck in that Ken Burns' Civil War mode of thinking. We've written quite a few times that doesn't have to be the case, that you can find the thread of a good documentary story in even seemingly trivial events and mundane lives. In fact, that's often where you find the most interesting documentaries!