I'd say organisation is the key. Talk to the couple and see what shots they have in mind. also make a list of the shots you want e.g. Bride and Groom + parents, B&G + Bridesmaids, B&G+ extended families etc... This will be one less thing to try and remember on the day.

I'd be tempted to shoot in JPEG and RAW, it's easier to recover wrong exposures and incorrect white balance, but if things look good you can still just use the jpeg to save time.