Acting advice, I could really use some.?

Ok so it's obviously not a huge blockbuster film, it's just a movie that is being filmed in my area. They are holding open auditions for the lead roles. I fit the female lead pretty well physically. But I want to work as much as possible on my acting. I have taken a few acting classes, I practice at home quite a bit, plus I am a very emotional person so I can make myself look genuinley sad, angry, agrrivated, surprised, scared so easily. I want this so bad because I know, I have what it takes. I know I am not the best, I don't even know if I am as good as I think but I will do whatever it takes to improve. I only have until saturday. I am 16 btw. My friends are so super supportive of this and I feel so lucky to have them. I was wondering what things I can do to improve my acting skills in a week. So when the audition comes I feel confident. Chances are I won't get the role. I understand there are probably loads of people auditioning and there are probably some with incredable acting skills that worked for this all their life. But I have a chance and that chance is all that matters. Please, what can I do? I was thinking of being my character for week. Acting the way she'd act, saying things she'd say. She and I have a few things in common which makes me feel pretty connected to her. I mean sure it'd be a little odd me coming to school as her, but I don't care. I just don't want to blow this. advice?