The key to success is preparation. We covered advanced planning in the last tutorial, so you should have gone all the groundwork. At least a day before the wedding, check that all your batteries are fully charged, all your memory cards are formatted, and that all your equipment is in perfect working order. Lay out everything you're going to use on the day, and pack it into your kit bag in such a way that you can quickly find anything you need. Remember the little things, like cable releases and remote controls if you think you'll need them. You aren't going to have time to hunt for things on the day, and the couple really don't want to see you panicking because you can't find the mounting plate that attaches your camera to your tripod. Your camera and lenses should already be spotless, but take a lens brush and a cleaning cloth anyway. You never know, it might rain.
Rather than taking everything you have, just take what gear you're actually going to use. It'll make it a lot easier to find things when you need them, and it'll keep your mind focused on the job at hand, rather than thinking about what bits of gear you might try next. A wedding isn't a place for experimentation; you should already know exactly what shots you're going to take.
Look The Part
You may be confident that you can do a professional job, but you want everyone else to know it too, so make sure you look like you know what you're doing. Wear your best dark-coloured suit, which you have hopefully remembered to have dry-cleaned, and men should wear a smart tie, preferably something plain and businesslike. Get a haircut, and men please remember to shave that morning. You should aim to be one of the smartest-dressed people at the wedding. If the bride's mother doesn't compliment you on your appearance, you're not doing it right.
The only exception is your shoes. You're going to be on your feet all day, so wear something presentable but comfortable. If the weather's against you, you may also have to move about on surfaces which are wet and slippery, and you really don't want to slip over in front of a couple of hundred people, especially while carrying an expensive camera, so wear something with a bit of grip. I use a pair of lightweight black Berghaus hiking boots, which go surprisingly well with a black suit.
You need to be on hand to record all the preparations on the big day, so you'll need to be there from the very start. Most of the preparations will be taking place at either the bride's or the bride's mother's house, and this is where you will arrange to meet. Arrange a time to be there, and make sure you're on time. Make sure you've got a contact number for the bride, the groom and/or the best man, so that if you are delayed by some unforeseen circumstance you can at least let them know you're on your way.