Wood
Floors, joinery and furniture. Pick one and let it run through the whole plan.
Stone
Worktops, floors and wet areas. Honed wears better than polished.
Fabric
Upholstery and curtains. This is where a scheme becomes comfortable.
Metal
Ironmongery, lighting and frames. One metal per room, ideally per house.
Paint & Plaster
The largest surface in the room, and the one chosen last.