Designers advise starting with function because a room must first serve the people living in it effectively. Assess how you use the space—seating needs, lighting for tasks, traffic flow—before adding decorative elements. This priority ensures comfort and practicality, making beauty an enhancement rather than a compromise. For example, adjusting furniture layout for smooth circulation or choosing lighting layers that support activities creates a foundation. Designing with function first leads to welcoming rooms that look intentional and feel personal over time.