Shopping throw pillows by color is the quickest way to find the one that belongs on your sofa. Most of ours are organic cotton, with linen, velvet, wool and silk in the mix, and the shades are dyed to look like fabric rather than paint, so the blues sit closer to indigo and denim, the reds closer to rust and terracotta.
Not sure where to start? Neutrals layer with everything and are the easiest to live with long term. If the room already has a lot going on, one colorful pillow usually does more than three quiet ones.