Creative gifts are like makeup mirrors. Girls love beauty when they grow up. Giving her a fashionable makeup mirror can make her confident every day, and she can have enough energy to study every day, so that learning becomes energetic. You can also give her a set of beautiful clothes and shoes. These are better gifts. New clothes give people a lot of encouragement on the first day of school, and a new start.
It is not easy to go home from a foreign place. You can bring her more local specialties, or send her snacks from home frequently. You must know some of your sister's habits or some things she likes. You can take her shopping a few days before her school starts, and buy her things she likes.
In fact, as long as you can care about your sister all the time and let her feel the warm family affection when she is away from home, it will be the best. It doesn't matter what gift you give as long as you have the intention.