A green screen is the base for any good video effect. But a green screen isn’t a easy thing to do, mostly if you want a good result at the end.
A classic setup for a green screen is a green surface behind an object/person which is filmed by a camera. The goal of filming on a green screen is to isolate a color from an image, so, a subject from is background so it can be changed at ease. The important in a good green screen is to have as less green on your subject as possible, a uniform green screen and a good camera. So, if the person being filmed wear a green shirt, it will be more difficult to isolate the green behind him and the green on him. Green isn’t the only option available, if you have to shoot an army man wearing a green suit, using a blue screen will do a way better the job.
To achieve a uniform green screen, your green screen needs to be wrinkle-less, a good way of achieving this is having a sturdy and even frame and many clothes pin to stretch the cloth. Your green screen needs to light evenly and softly it also need a separated set of light than your subject, otherwise, your subject could create a shadow on your green screen.
To have as less green reflect on your subject as possible, your green screen needs to be at least three feet from each another. If the subject has green on him, the effect would be much more difficult to create because a part of him is now the same colour that we try to remove.
You need a good camera to film on a green. A good camera mean that you will have more resolution (the number of pixels in a screen) so a more defined separation between the subject and the green screen. A good camera also has a higher shutter speed (a higher shutter speed mean a less blurry video), which also, make the separation between the subject and the green screen more define but only when there is a fast movement from the subject.
The minimal material required are a green cloth, a frame to hang the green cloth, a subject to put between the camera and the green screen, 2-3 source of light and a camera (latest cellphone are viable).