TouchCast Pitch Windows : Chroma Key Green-Screen Best Practices

Choosing the right chroma color

Chroma green is typically the color filmmakers choose when they decide to do some compositing, but not necessarily because it's better or worse than blue (or any other color). Though there are plenty of technical advantages to using green, your choice should be based on the qualities and obstacles of each specific shot you're capturing -- and most of the time blue is found in the shot more often than green. Here are some tips Rosen points out:

• If there's green in your shot, choose a blue chroma color. If there's blue in your shot, choose a green.
• Green is twice as reflective as blue, so it tends to contaminate your shot more.
• If your background is blue or green, use those respective colors for your key color.
• Most modern cameras have sensors that use the green channel to carry luminance, so shooting on a green screen could result in twice as many pixels.

Don't overexpose the chroma screen

Make sure that you are more exposed than your green-screen so that it's you that's being highlighted and not the green screen.

The cleaner the green screen, the cleaner the key

Other than green or blue fabric, the next most important tool to have on you when chroma keying is an iron, or anything that will help you flatten those creases and folds in your screen. 

One-click keys

Essentially, if you've done everything right -- you've chosen the right chroma color, exposed correctly, shot against a clean screen, and chosen the highest possible compression format you can -- you should be able to isolate your chroma color in one click when you begin the post process. See, every aspect of chroma keying is important, because they all influence the final result. A one-click key means you put in the work to do it right the first time.

Reference: https://nofilmschool.com/2015/09/5-secrets-pulling-hollywood-level-chroma-key-besides-good-lighting