Remove spills immediately, by first scraping up as much of the substance as possible with a plastic spoon: scrape towards the center of the spill. If the stain is in an obvious area, consider doing a spot test in an inconspicuous area first. You can do this simply by soaking a cotton ball with water, and lightly dabbing it on the pillow. If the colour bleeds, take the pillow to a dry-cleaner. If the colour does not bleed, you can spot clean it.
For spot cleaning add a few drops of mild dish soap to lukewarm water. Stir until it becomes sudsy, then dip a cloth into the water. Use the damp cloth to blot up the stain. Blot up any soap residue using a clean cloth dampened with fresh, clean water. Let the damp area air dry thoroughly. In case the pillow cover could not be removed and you are concerned about the fabric fading, let the pillow dry in a shaded, but well-ventilated, area.
To maintain the original softness and resilience of the pillows, hand fluff regularly.