Well, if you are about to become a bride and your friends are organizing a hen night for you, then It will be your friends who will be deciding the theme for the party and You will just have to follow whatever they decide. As the bride to be, they may have already decided what dress you are supposed to wear. If the hen party is at a friend’s home, at the beach, in a club, or if you are going out, they will already have made the arrangements. So, you don’t have to worry about what you are going to wear.
Conversely, if you are organizing a hen party for a bride to be, then you better consider of what theme you would like for the party. Keep in mind, the common idea of a hen party is to have a lob as friends before your buddy gets married and after that choose as to what style of party you want to have. Commonly, a hen party is a fancy dress party.