Just wanted to comment on the wear nude underthings. This is a must! I can't tell you how wrong it is to be going though initiation or watching it when someone forgot and wore a red (lacey) bra, a red thong, black thong, black bra..... the list goes on (mostly with respect to color).
Pure white underthings often show through when the dress is of thin material, so stick with whatever is closest to your skin tone.