Hey Travis,
Wife and I did weddings for a long long time. Here are a few tips:
1. Always wear sunscreen...
seriously though:
2. Back-up... have backups of everything (cameras, lenses, batteries, storage, and an extra photographer if you can)
3. Flash - More is better, to get a more natural look, bounce your flash against ceilings and walls, instead of straight from the front. That requires a bit more oomph
4. Good shoes - you are going to be on your feet for 8-12 hours
5. Water - keep hydrated, if you are hydrated, your brain is hydrated, which means you work better under presure, and your responses are generally faster, and you don't get so tired, and you are generally less iritated. (no alcohol on the day... trust me)
6. Travel light, but don't leave anything at home that you might need. You have to be mobile, and you have to be able to move fast.
7. Don't interfere, it's somebody's wedding, not a photo shoot. Shoot fast, don't take up their time. shoot with long lenses during ceremonies (hide behind flower arangements and potted plants)
8. If you want to buy something, buy a reflector, great for bouncing flash, and adding natural light to a scene
addition to point 2: If you can, take a second photographer. So many things happen in so many places, and even if you run from spot to spot, you will only end up tired, and still miss half of everything.
Hope that makes sense?