The most important thing you need is a suitcase. If I had a girl, I'd get her the wandering star luggage ($98), which I love, and since I don't have girls, I'll probably just get it for myself!
But I got [the boys] these amazing suitcases that they pack themselves. These Jellybean suitcases are small sized, on four wheels, and totally lightweight. I encourage them to pack themselves. They pack the books, the toys, and the Legos that they want to bring with them. And then, obviously, they need a little help with the underwear, the swim trunks, and the things that they don’t think about!