I'm in a similar situation - I've not been the primary shooter at a wedding, but have taken my camera to a couple and got a few ideas from that. I have two weddings coming up where I will be the main photographer, and found this checklist which I think will be useful.
http://www.all-things-photography.com/support-files/weddingchecklist.pdf
The few things I've learnt are; as said before, be assertive about what you want people to do, take loads of cards (I'm got 6, and I'll take all of them and more), spare batteries for everything, and see if you can beg/borrow/steal a second body. Make sure you know how to use every bit of equipment you'll be using inside out and preferably by touch, and take a laptop - I think it'll put my own mind at rest to know that I'll be able to check a few shots here and there as the event goes on and uploading them as the event goes on gives a level of security against images being lost.
Advice I've read online includes take gaffer tape, rubber bands and a small torch for yourself, and lip gloss, a small sewing kit like you get at hotels, scrunchies, hair clips and bands for others - apparently, it's surprising how often people need these things and having them can really get people on your side and willing to help, i.e., by holding a slaved flash for you. Work out the shots you want, and if possible rehearse them first. This avoids missing shots you really need to get. Find a safe, out of the way place you can leave your stuff where it's not going to get drink spilt over it or pilfered. Be prepared to ask other people taking pictures to give you space, everyone wants the same shots but you're the one taking the 'official' ones so you have precedence. I read it works well to make a deal with other photographers where they let you take your shot, then they take theirs before you move the groupings etc around. Might be an idea to get people to email you their shots as well for the album - there'll be some great pictures taken by others that you'll have missed. One of the best albums I've seen was from a wedding where we were all given disposable cameras which were left at the venue, and these were interspersed with the pro's shots.
If you've got the money, maybe consider getting a lens for this, one you'll use for other purposes. I bought a Sigma 24-70 2.8, the non-HSM version. I did a lot of reading up, and there seems to be a consensus that a lens of that range is very well suited for most parts of a wedding. The two in my price range were the Sigma and the Tamron 28-75 2.8, but I experimented with my kit lens and found that I'd really miss the 4mm at the shorter end, and preferred the build. I love it, it's now my most used lens, and having bought it ahead of time I've had plenty of practice with it to learn how to get the most out of it. It's got a great range for portraits to small or stepped back group shots so I can see how useful it'll be.