Prom look help!!

I need help!! I have a prom in 2 weeks and need advice. Last year I was voted most beautiful date AND most beautiful dress. This year I have to be equally as gorgeous. I have a dress that is black and strapless. I have not decided about my hair or makeup. I dont want to look "gothic" I want to be as pretty if not prettier than last year. I cant decide if I want my hair up or down. I am having extensions put in so I can do pretty much anything with my hair. Any suggestions are greatly appreciated. I need help with the makeup look, the hair style, and jewelry. I already have shoes!!