i need advice about birthday gifts..

What is a debut? Turning 18 she gets to find a place of her own, correct? Anyway, what does she like. Perhaps a journel and a nice pen or two for her first yeat of being an adult. How about a favorite perfume. You should know of her better so that could lead you to something. Also you could ask the mother. She should really know. Good luck with this one.

If you don't know her that well, why not get her a gift certificate to a trendy store nearby? You could also go for an elegant journal with a pen, a basket of lotions and oils, or a book like Chicken Soup for the Soul, or something similarily uplifting.

If you do not know her much, well what you could get her is gift certificates from any music store, I'm sure she likes music at that age. You could also give her money and she could buy what she wants wit it.

you could maybe buy her a bottle of perfume and a birthday card. she would appreciate your gift very much

most 18 years I know appreciate money. If that doesn't work, a gift card to something they like to do (movies, bowling, restaurant, etc.) or a gift card to their favorite store. another thing I have given to special people is a "day with me" (could be an afternoon, morning, whatever). we do things together they like to do, buy them lunch, see a movie, shop, whatever....I think the gift of time is what is important in this instance.

some beautiful flowers would be good enough

hmmmm...can be fashion cloths or makeup or some nice perfume ;)