Good teen hair cuts are layers for girls and short maybe spiked for boys. Girls like layers because they can have angles and shapes with any style they choose for their hair that day. For boys its easy to not do anything with short hair.
A great look for teenage girls is to wear their hair long with a bunch of loose curls/waves. It gives them the sort of messy look, will still being pretty and cute.
The best teen hair cuts are a little bit below the shoulders. This is the perfect type of teenager hair style. You should tell your daughter to get this type if she wants.