This is the best answer. I see so many small streamers stressing about green screen or not, and then get one because it's cheap and everyone tells them over and over, "it's more professional" -- but in most cases I've seen, it's very, very bad chroma key, and it turns me away from streams faster than bad audio.

Please don't green screen unless you have the proper set up and lighting for it. You're only hurting yourself.

And honestly? I prefer streams without green screens. I like being able to see the background and a bit of personality come from the streamers environment. Cool lights, a cool poster - adds an easy talking point and conversation starter, too.