Regularly dusting or vacuuming your throw pillows as you vacuum your upholstery will keep them from needing cleaning for a longer period of time.
Also, using throw pillow covers in coordinating colors also makes it easier to clean them often, especially if they are machine-washable – as you won’t need to worry about dark dyes mixing in with lighter whites.
Finally, keep hard to clean throw pillows above ground and in harder-to-reach places, where dogs, cats, kids, and people’s feet won’t soil them frequently.