I think you're going to be driven crazy enough just trying to keep up with your load of classes, let alone taking on a persona that you think is what everyone wants to see. Just worry about being respectful and being yourself. If you think that you'll make a great nurse (and I hope that you do, seeing as you're going to school for it), that will just come through naturally. I don't know what you would characterize as "aggressive," but you should never be afraid to ask and answer questions and to challenge yourself! It's important and beneficial for you to stand out among your peers... and that's true of any academic pursuit.