Depends.. Whats your style? Are you slightly chubby or skinny..? For my grad, i bought a beautiful dress from Supre! It was white, short and silky. See other shops such as Myer or Ice. Ice isn't...
Maybe look in Myers as they will probably have pretty dresses! I'm looking for a dress too, my graduation is coming up... I'm so nervous. You could also try dotti, I know my friend found heaps there.