Article: They typically come custom-cut.  (In a pinch, see the "Tips" to cut one down to fit.)  There are a few basic materials:  Semi-hard, slick, clear soda-bottle style such as PET, the most common and generally best. (Gimmicky variations such as semi-reflective or matte can be fun, but less practical.) Very hard, clear tempered glass, like a stronger microscope coverslip.  Should have a plastic layer to hold together if damaged.  Extremely scratch resistant, but brittle; tends to flake apart progressively once chipped. Very tough, thick plastic such as polycarbonate.  Provides direct impact protection.  Not very scratch resistant--won't stay pretty.  May reduce accuracy of touchscreens. Soft vinyl plastic.  Not recommended as generally less pleasant to use, but does prevent scratches. Anywhere indoors with calm air is a good start.  You can improve things with steam. Running a hot shower works well, which fills the room with steam. When the steam has subsided, there will be less dust in the air than usual. This is the best time to apply the screen protector.
What is a summary of what this article is about?
Get a screen protector. Find a low-dust workspace.