First, “Take everything off the shelves and start fresh,” advises Katie Raffetto, who has her own design firm in San Francisco. Next, place books both vertically and horizontally, sprinkling the two methods throughout (pull the spines all the way to the front of the shelf so they look even, or turn so backs face the wall). Stand back periodically and look at the mix—and don’t overcrowd! “If you wean out, it will look so much more fresh and new,” Raffetto says. Next, add objects to fill in the holes: little sculptures, baskets, decorative boxes, ceramics. Try to keep them within a broad color or materials palette to make the whole look cohesive.