it depends what kind of look you want to go for.
edit: oh, well i guess you're a guy

i'd go for a white, black or dark grey tux. if you're wearing a black tux don't wear a white shirt with it.
i'll leave this down for girls. v
bold: turquoise in satin only, or red.
wintery: white, light grey, silver, icy blue or icy blue
festive: gold, red, dark green

the type of dress is a whole other story