When you get right down to it, there are two types of virtual theatre: the shows with a green screen, and the shows without one. Depending on what "look" the production is trying to achieve, a green screen may be something a director asks their actors to provide (as opposed to a blank wall or a bedsheet behind you). Depending on how it's used, a green screen can be a wonderful feature of a performance, or one that is a huge distraction.
The first thing to know is how green screen technology works: Your computer camera sees the striking difference between your skin tone and clothing, and because it's able to discern the "layers" of color, it places an image over the green layer.
TIP #1: COLOR
The term "green screen" is so often used to describe the color of the backing fabric because that was just the one most often used when this technology started being used. But your screen can be blue, red, or even white! The reason why green is the go-to color -- apart from the rhyming nature of the term -- is because very few skin or clothing tones match that precise shade.
TIP #2: CHROMA-KEY
This might be a term you've seen used when shopping for a green screen. This means that it is a very precise shade of green, and a particular type of fabric, that has proven to work better. When possible, make sure your screen is chroma key.
TIP #3: SIZE
Depending upon how you use the green screen (Will you always be sitting? Do you plan to be standing? Moving?) the size you get is very important. If you plan to stand or move around while on camera, you should get a green screen a few feet taller and wider than you, unless you want the camera right in your face. (10 ft X 12 feet is usually a safe bet). If you will always be sitting, smaller ones (like those that attach to your chair) can work for you. The worst thing to happen is that the size is too small, and your camera catches the area around it. Go big, because even if it's on the floor, you still are covered.
TIP #4: NO WRINKLES
In order to work best, green screens must be smooth, with nary a wrinkle in sight. When there is an indentation, albeit a small one, a shadow can be formed, which will confuse the camera and cause a portion of your screen to "drop out" or pixelate. Unless you leave it hanging up, keep it folded up neatly, and iron it if necessary.
TIP #5: LIGHTS
As mentioned previously, wrinkles are your enemy...but so is darkness. So to combat these evils, use strong lighting evenly across the whole green screen. And we don't mean just lamps and flashlights. The brighter you can make your performance area, the better the result will be. So consider buying some lighting fixtures akin to the kind professional photographers use. You don't need to spend a lot to look your best.
Keeping these tips in mind, you can buy a green screen that will not bankrupt you, but make you, and your production, look its best!