Hi Hi,
You've a lot of choice !
參加人地既婚禮 , 其實可以wearing some colorful dress 加一條依家好興既頸鍊 OR 外襯衫 or 披肩 being very OK ge !!!
Suggested you visiting the below links with photos bring you some idea for Young & Smart + Elegant look for go to 參加觀禮, 飲宴 !! It won't make you looks over dress !