C.A.
Can you take her shopping so she can choose some items for her room like a comforter or lamp, wall art, etc... Something so she gets to choose how her space looks. The shopping trip will be a bonding time. I don't think you have to go crazy and spend a lot of money either. I recently saw at Walmart comforters under $20.
Good luck! She is a lucky girl to have such a wonderful step mom that is welcoming her with open arms.