I received a recent inquiry about couch pillow placement; how should they be placed and the maximum amount of pillows you should add. My personal rule of thumb is place as many pillows on your couch as long as you and your guests are still able to sit comfortably. Of course the bigger and plush the couch the more pillows you can add but don't go adding 50 pillows to where your guests end up sitting on the floor. You can mix and match your pillows from geometric patterns to floral design. My tip is if you do use several patterns, break up the busy-ness by pulling a solid color from one of the pillows to tie it together and make it a little easier on the eyes.
in this photo: trina turk pillow embroidered linen jungle bloom gray/blue
dl rhein mod link robin's egg embroidered pillow bindi stripe swoon dl rhein mod link robins egg embroidered linen pillow
As far as arrangement, It highly depends on your organization style. If you have a casual design with a room full of mix matched patterns, I say randomly place your pillows on the couch just like this...
If you have a very detail organized room neatly coordinate your pillows..
There's nothing wrong with a single pillow. It adds a simple compliment to your couch. Another rule of thumb, if you have leather couches, select soft plush pillows. The soft texture breaks up the cold feeling of the leather couch and brings warmth and comfort.
If you a have super sleek contemporary couch and you want to bring in some warmth, bring in matching pillows such as these to make for an inviting seating area. There is nothing more cold and uninviting than leather on leather with white on white.
in this photo: Thomaspaul - Mod Mex Banner Violet Pillow