Firstly, everyone is a bit nervous in front of the camera, it's totally normal to feel a bit anxious. The biggest thing you can do to help with this is to choose a photographer who puts you at ease and makes you feel comfortable. Have a chat before the wedding to go over any worries, and they will be able to help you. It might be worth having a pre-wedding shoot too, this is a short photo session before the wedding, which will help you get used to having your photo taken. The main thing is to relax and trust your photographer. They will put you in the best light, guide you through any poses and help you look relaxed.