I would recommend Tanya to follow the general rule of fashion proportion: a big top needs a small bottom part, and vice versa, but a tight T-shirt and the trousers she is wearing make her look like she has grown out of her childhood clothes. The blue color of Tanya's top is OK, because if she puts on something in very bright colors it will brake the school dress code. I think Tanya's top lacks some patterns. For example flowers, lines. I would recommend Tanya to add some accessories to her outfit. For example as it Nastya has done (see the bracelet on her wrist).