What Responsibility's Did A Princess Have In Medieval Times?

The main responsibility was to attract a wealthy suitor who hopefully not only had wealth but a kingdom of his own.  This way both kingdoms were strengthened.

The princess not only had to be beautiful and wear attractive gowns she was also taught how to speak correctly, how to greet people, and generally behave well in company.  She was taught painting, sewing, singing and how to play musical instruments.  She was taught how to dance and ride.  She was also taught about food and plants.  The princess was well educated in all respects with impeccable manners.