Instead of buying new, focus on repainting existing furniture or finding unique pieces at thrift stores [0.5.2).
Beyond aesthetics, building a "solid" foundation in lifestyle and skills is critical during the teen years:
Balance roomier, oversized pieces with slimmer items to maintain a visual harmony that doesn't "swallow" the wearer.
Balance overly "sweet" or feminine elements with sharper pieces to ensure the look appears mature rather than childlike. Health & Skill Foundations