Take things slow and relax
If you take half a second to exchange rings and kiss after the Ceremony, it will be harder for your photographer to get good shots ;p
Exchanging rings
Gently cradle your partner's ring hand with your free hand. All your hands should be relaxed. When you are putting the ring on your partner, please try to hold the ring between your thumb and finger, with your hand lower than your partner's hand. It is also best if you can keep your hands at about the waist level of the shorter person. The ring is less likely to be blocked this way.
Kissing
Try not to pucker up your lips when you kiss as it tends to look unflattering in photographs. Instead, you can both slightly tilt your heads and gently bring your faces together to kiss.