A unique wedding photography skill most photographers ignore is to have their workflow organized. It really makes a huge difference. Keep charged batteries in a separate compartment in your camera bag/photo-vest, away from the one for discharged ones. Similarly keep your fresh memory cards in a separate pocket, say your right top pocket, and the filled cards in, say, your left bottom one. This helps you switch cards without committing errors and wasting precious time. Ask your assistant to immediately take a backup of the photos as soon as a card is filled, in a portable hard drive. Again at the end of the day, consider burning all photos onto DVDs and post/courier them to your studio/residence, just to ensure the images are safe even if the card gets corrupted/lost/stolen.