Help with Black Sweet Sixteen?

I'm having my sweet sixteen at a local banquet hall, and I need some ideas of decorations, and activities. I'm having tables set up for people to eat, a place for gifts to go, ect. my colors are black and purple, i'm having the dress code to where everyone wears black, semi-formal(then i'll be the only one wearing purple:D). and i want accents of purple in the decor, but i don't know what to do!!