Chroma key can be very helpful when you lack the budget to shoot your film at a tropical island or other location. With chroma key, it’s a cheaper option to bring that location to a studio. However, with a green screen you may run into some technical issues.
Using a green screen will shorten production time, eliminating the need to change backgrounds after each scene. This also decreases the cost of your production. If you already have a photo manipulation program such as Photoshop or Pixlr than you will just need to provide the colored background. A background can be a green or blue sheet or as simple as paint on a wall. The backgrounds themselves will just be saved photos that you have.
Green screen can make your production easier but far from simpler. Adjusting to the process can be very difficult and complicated to learn and other issues can be formed from the subject itself. Subjects with shades of the color that matche the colored wall behind your talent will be slightly see-through. This can easily avoided by informing the talent before the day of filming. Another issue can be formed by a line around your subject where the screen meets the talent. This occurs often with long hair.
Green screen is a process that can make the crew life easier in some cases but more difficult in certain situations. If you are intending to use the chroma key process, you should educate yourself on certain procedures in order to prevent a complicated production for your first time.