Name the activity before the room.
An office, music room, art studio, fitness space, and dwelling can need different building features. List the actual activities, equipment, visitors, and expected hours of use before selecting a plan.
Design around furniture and equipment.
Measure desks, tables, fitness equipment, shelving, and the clearance needed to use them. Review delivery access and any specific electrical, plumbing, ventilation, or other requirements during design.
Control the light and distractions.
Consider screen glare, the direction of daylight, lighting for detailed work, acoustic priorities, and privacy. A view can be valuable, but the window arrangement should also serve the task performed inside.
Define comfort and future use.
Heating and cooling, storage, bathroom access, and the connection to the main house affect everyday use. Discuss possible later uses without assuming that a studio can become a dwelling without additional review or work.