I now have a camera that I'm quite satisfied with, and also a couple of different microphones for recording audio that doesn't sound horrible. However, something I haven't paid attention to yet is lighting and I have the feeling I could improve the quality of my shots dramatically by starting to think a little more about this.
So, given that I'm on somewhat of a tight budget, is there some piece of equipment that would be great for all-round use when it comes to lighting, both indoors and outdoors, at day and at night? I realize that you will have to acquire a whole truckload of gear to actually perfect your shot, but given that you only can start out with one piece of equipment, something that might come in handy during many different scenarios (like duct tape is to the engineer), what should you invest in? Would a strong flashlight be of any use? A big piece of white cardboard to reflect already present light? A couple of logs and a lighter to create instant bonfires wherever you are?