To dream about a girl indicates the side of you that is pure, frisky, and trusting. You may have been acting a bit too prematurely.
To dream about a girl that you just met suggests that you have concerns and fears about whether she thought well of you. If you dream that she does not like you, then this may be a way for you to decide to not pursue anything beyond simple friendship.
For a man to dream that he is a girl indicates that he wishes to become an actor that plays only female roles.