The only essential tool for furniture shopping is a tape measure. Of course, you need to know room dimensions, but that’s not enough. Create a detailed floor plan (including molding and electrical outlets) showing where each piece will go and what size it should be — including length, width and ideal height, Panis says. Try different sofas and chairs to find a comfortable seat depth, size and scale, and note the dimensions. The same goes for the depth and height of a coffee table or dining room set. Also, measure every door, hallway and entry point in your home to ensure you can get furniture into the space.