The first element in pulling off a key is the type of space you have to work with. Your space will determine what kind of chromakey shot is possible. When shooting against a greenscreen or a blue screen, you’ll want to pull you subject away from the background far enough so that shadows don’t fall on the screen and you’ll want to minimize the reflection of the screen on your subject.<
With smaller spaces you should be able to pull off a reasonable talking head shot - that’s where the shot is just the head and shoulders of the subject speaking. For a full body shot, you’re not only going to need a larger space for a screen, but some distance to place the camera so that your subject looks natural and isn’t distorted by a wide angle lens.
Shooting outdoors is also a possibility especially for certain shots, just keep in mind you’ll have to deal with all the issues that come shooting outdoors including wind, noise, and shadows.
The first question you’re going to ask is green or blue? Blue screen was a traditional color in the film days and is still used today for many productions, but green is the preferred color for digital keying. Why? Because many digital cameras use a Bayer pattern of Red Green Blue photosites where there are twice as many green photosites as there are red and blue. This makes digital cameras much more sensitive to green coloring. Green screen also requires a lot less light than blue screen and is less likely to match the clothing of your actors.
Still you may want to use blue screen in certain cases - say you’re shooting a green monster. In fact on the Sam Raimi’s Spiderman, The Green Goblin had to be photographed on a bluescreen because the suit would have been lost on a greenscreen. Spiderman on the other hand had to be shot on a Greenscreen, because his suit was red and blue..
When it comes to the material of your screen you have several options. The first is to paint your background using a chroma key paint. This is the most permanent although labor intensive way to create a chromakey background though certainly necessary if you are planning on installing a cyclorama.
The other option is to hang your screen You’ll need background stands and clamps to hang your screen on. The screen itself can be made out of paper, or muslin background cloth, but I prefer foam backed cloth because it scatters the light more evenly so you can avoid hotspots and the foam keeps the screen from wrinkling when not in use.
For small setups, foldable chroma key screens are available. These kits are really handy for quick portable setups or outdoor use and built in frame keeps the screen from getting too wrinkled.