When it comes to outdoor areas, pillows with bold prints are popular. A combination of different prints looks fabulous in an outdoor setting.
I prefer to use odd numbers of pillows — for example, two on one side and one on the other side of a standard four-seater sofa. For a larger, modular sofa, I’d recommend two on each side and one or two in the middle so that each part of the sofa has a pop of color.
I use the same method for bedrooms: the large-size combination on a king-size bed and the small-size combination on a queen.
As a general rule, odd numbers of pillows work well in a casual living room, while even numbers will give a formal living room the symmetry it requires.
You can also have too few pillows, which can give your room a cold, sterile look. One pillow on a large sofa or king-size bed, for example, is definitely too few. You would only ever have a single pillow on a statement chair or a single bed.
Article source: https://www.houzz.com/ideabooks/97978520/list/throw-pillow-master-class-how-to-choose-and-style-like-a-pro