Cool Guy Walking Away From an Explosion

Hey, I'm in the pre-planning of a video and one of the things I am planning to do is a cheesy end part where the hero walks out of a big barn door as it explodes and I'm looking at what green screen to get for it. I'm going to be testing to make sure I get a good key on my laptop before we film so are there any major things I should be aware of (Besides making sure there is good lighting on the green screen)?  What I'm not sure about is which green screen to buy. I'm leaning towards the big ones on stands but is there any reason I should get something else?

I know the basics of green screen but have yet to implement it in anything I'm grateful for any thoughts or suggestions.