Anyone here ever have the opportunity to shoot a wedding?

I'm supposed to be doing one soon, but I'm having mixed feelings. You, as the photographer has a chance to capture this one in a lifetime event.

Your Job is to...

* Record the day in the way they want
* Keep things running smoothly
* Know how to deal with and cope with any situation that may arise
* Get on well with their guests
* Get the job done
* Do it while not getting in the way
* Be efficient, on time and smart

...And much more I'm sure. But all of this scares me. If something goes wrong in one of these avenues, its all your fault.

There are 2 things that could happen, which makes me nervous.

1. You could totally nail the shoot. Getting every picture in every way you had hope. Opening the way for more clients to come your way after the wedding parties referrals.

2. You could totally drop the ball. And the wedding party is unhappy. Closing the door for further clients. And not capturing the moment most important in these two peoples lives.

With that being said, has anyone ever shot a wedding? If so, is there anything you did or didn't do that you wish you would or wouldn't have done?
Any tips or pointers?

I don't remember anyone posting about shooting a wedding, but if there are any tips you may have found online,books...etc. Please share.

These people are paying a lot of money for this.

Sorry for the long post