Do not say HI for starts say Hello it is more professional ,I am an english major and then your name and sound excited,up beat and why you are an English major I chose to be------------ and what your goals are children's lit write books poetry excites you authors that are an inspiration,remember you are not just speaking to a class you are introducing yourself to a class. If my wife was here she would be better at telling you because that is her major,and she is going for her Masters,me I am speaking from what she has had to do.
Down the road,it gets harder,you have to introduce a classmate,and speak about them etc.