Stripped of its contents, an empty room can be intimidating, or it can be inspiring. For design consultant Robin Long Mayer, it’s definitely the latter. In her work as an editor for Country Living and New York Spaces magazines, and as the principal of Robin Mayer Design, she has learned a thing or two about the optimal placement of sofas, tables, beds and everything else that makes a home. While the ideal arrangement of furniture depends on myriad factors—the size and layout of the room, for staters—these guideposts can put you on the right path. Bon voyage!