Space planning sits a level above furniture layout. It's the question of what each part of the available space is for: where do we cook, eat, host, sleep, work, store, transit? Good space planning happens before furniture is even considered, because furniture choices follow function.
The practical method: walk the space and notate use zones. Where will the morning routine happen? Where will guests sit? Where will the kid do homework? Where does coat-and-shoe traffic flow? Once those are placed, the floor plan reorganizes itself — walls might want to move, openings might want to close, fixed elements (kitchen island, fireplace) might want to relocate or stay.
Space planning is especially valuable in renovations and small spaces. A 600-square-foot apartment can feel cramped or generous depending on how its zones are organized. The same furniture placed differently can make a one-bedroom feel like a small studio or a comfortable home.