What Always said.
Plus,
practice practice practice. As many times as you can.
Not with friends, with adults. Your advisor, a professor, a parent, a boss, your school's placement center. Give them questions to ask you (which correspond to the questions you had in prior interviews). Plus, have them ask questions they make up that you are not anticipating. If with some prep you can't nail them now, a second or third time ......
Do some internet research on how to prepare for an interview.
Good luck