First of all I should point out a few common points that I knew about wedding photography before I began. Hopefully these are things that you know too. If any of them take you by surprise think very very carefully before agreeing to photograph someone's wedding.
1) Wedding Photography is more than taking photos on the wedding day
Good wedding photography requires you to scout out the location for the formal shoot, the ceremony, and the reception. This way you'll know where to take photos. If you can attend the rehearsal you'll also get an idea of when to take photos. It also involves post production work. While I don't airbrush my images I expected to (and do) apply corrections to every image I expected to pass on.
2) Weddings and Wedding Photos tend to be very important to the bride and groom
So you should be prepared, in terms of skill and spirit, to take on the responsibility of capturing this day.
3) You need reliable gear
4) You need to know your gear
You might like to check out this guide to wedding photography gear.
With those common points out of the way here's some information that you probably won't find when reading something written by a photographer who has been shooting weddings for years:
1) Photographing weddings will be utterly terrifying and you probably won't sleep.
If you're thinking about photographing weddings
2) Take your own advice
Eat, drink, and try and sleep ahead of the wedding. Eat and drink at the wedding even if you don't feel hungry or thirsty. Take a water bottle with you in your bag.
4) That reliable gear you have will be really heavy by the end of the day
5) You will sweat
Use a quality deodorant. The best one I've found is a deodorant block available from Lush
3) You will be useless the following day
The combination of a lack of sleep, heavy gear, and a whole day on your feet will mean you will be sore the following day. Schedule nothing and use the time to load the photos onto the computer and back them up.
6) Synchronize your watches
If you're using 2 cameras at once make sure that the clocks are set to the same time - this should include the date. This way when you get home you will be able to arrange the files by date.
7) Rename your files
Once your files are arranged by date rename them to ensure that this structure remains
8) Invest in quality equipment early on - avoid parallel imports
This is a lesson that I learnt the hardway, kind of. I started off with a parallel imported 24-60mm sigma lens as my main lens. At the start of 2011 the autofocus stopped working. As it was a parallel impport it had to be sent overseas to get repaired, a process allegedly taking up to 4 weeks. I'm still waiting for it to come back and bought a Nikkor 24-70mm 2.8 immediately after it was sent away.
