How do I act like Mary Santiago (Selena Gomez) from Another Cinderella Story?

The reason why I want to act like her is because Im going to a new school and people thought i was mean at my old school so I kinda want to change my image I don't want them to think of me the same way. So i want to be like her nice and quiet But i dont really know how to cause i forgot so please......HELP! ;)