There's newer styles of covering weddings, such as "photojournalist style", to consider, but most people still want the traditional approach. For that, get a good paperback book on doing it, mostly so that you will have a checklist of all the shots to get. David already gave you good advise on cameras/lens/flash setup and use.
When setting up for the processional, (bridesmaids and bride coming down the aisle), I always either put a small piece of masking tape on the floor or used another marker, like a candelabra, and told them to pause for a second until they see the flash go off. In the film days I was always pre-focused there. Also, take those shots very wide, so you can crop them either way. Most people will want them portrait orientation, so hold it by the Vgrip and you'll loose less pixels.
Remember when doing all your posed shots that the bride is least able to move because of the dress, so do all your shots with her first - bride with attendants, her family, his family, both families, Bride and Groom with hers, his, and both, etc.... Use a tripod and a remote for these shots.
Next remember that anyone not officially in the wedding feels imposed upon to be there getting their pictures taken when they could be drinking at the reception, so get them out of the way next.
If you can set a tripod in the balcony for an assistant to capture the lighting of the unity candle w/ a long lens, great.
Don't forget to take the rings laying on the program, the signing of the license, and all the little ones that make it a big deal for the couple. Take extra shots because there's not cost for film or developing. In the film days we were told to get it right the first time, and don't shoot another unless you think it was a bad shot, to keep the cost down.
Take a deep breath, suck it up and go for it, unless you trip over a candelabra and catch the church on fire, the wost you can do is give them crummy pics.