Add or remove a skirt: While exposed legs look unmistakably modern, covering up the legs by adding a fabric panel can make a sofa more formal or make it shabby chic casual. Or, remove the skirt on a couch to expose its legs and lighten it up.
Add or remove cushion buttons: An upholsterer can easily add buttons to the back, seat or both cushions of a couch to bring it from informal to more tailored. Removing buttons can relax the look of your sofa.
Add bolster pillows to a couch: Give a sleek modern couch a bohemian look by adding bolster pillows on either end made of the same fabric.
Take your couch from tight back to cushion back: If your couch has a tight back, try loosening up its streamlined vibe by adding 3 Euro-sized pillows across the back
Try a slipcover: You can buy a standard one or have your upholsterer tailor make one for your couch. I'm cosidering having one made out of white duck (along with cases for my couch's loose cushions) so that next summer I can quickly morph my sleek metal legged modern sofa into something beachy for summer.
Image: Kyle Freeman from Rich and Emily's Somerville Surprise