What should I wear to My Advent Service?(the attire is dressy)?

ok, it's an advent service at a church. the attire for girls is a nice(but not too nice) dress, or skirt with nice shoes, i'm thinking heels. i have no idea what to get, cuz i don't really know the holiday fashions this year. well i know, but no for something like this. by the way, i have a solo, so i have to look extra good since EVeRYONE will be looking at me, thanks!