It's probably the most important then a woman's life, it's their wedding day. For thousands of years women have dreamed about their weddings ever since they were young girls. They have hope chests where they store special belongings that they hope to use on their wedding day and beyond, day by wedding magazines by the thousands, and they almost religiously follow celebrity weddings as if they were their very own. When that special day comes in a woman's life there is nothing more important to her than to look beautiful, and feel beautiful. They spend unlimited funds on their wedding dresses, wedding favors, DJs and getting everything for their special day to be just perfect. They don't want any errors, they want perfection and they plan their entire life for a beautiful day.
There's no doubt that during your wedding something inevitably will go wrong, and you should prepare for this in advance. I know of one particular wedding party where the photographer forgot what film and his camera and all of the pictures were ruined. Of course that isn't as much of an issue now with digital cameras, but still you never know when something might go wrong with something as simple as photography. You should plan ahead for things such as these perhaps even giving your guest disposable cameras to take pictures on their own. Just make sure that they dropped the cameras off in a special container whenever they leave your wedding.
Another problem that often happens at weddings is that the bride has a little bit too much to drink beforehand. This can really spell disaster for the entire ceremony if the wedding is really standing at the altar to smashed to even speak. They could also happen that the groom has a little bit too much to drink, or perhaps he's just feeling queasy from the excitement of the day and he passes out. Don't be surprised if something serious like this happens during your wedding, but just prepare ahead of time and don't take yourself too seriously.
The wedding day was made to be beautiful, and the most special day in a woman's life. Try and relax, take a few deep breaths before stepping out in front of the crowd, and relax. You will have a much more memorable time if you don't expect perfection and then you are overly upset whenever you don't achieve perfection. Just enjoy your day, make it special in your own unique way, enjoy the time with friends and family that you may not get to enjoy the time with as much as you should. This will set the stage for a wonderful life with your future husband.