Quick Answer: Plan new house interiors in this order: write down how your family lives, set a budget with a cushion, get a measured floor plan, fix the electrical, plumbing and ceiling plan, then order the kitchen and fitted furniture, and finish with paint, lighting and decor. Doing it in this order avoids breaking walls twice and keeps the budget under control. Key Facts: A common budget rule is to keep 10 to 15 percent aside for hidden costs (Home2Decor, "Interior Design C