1. Take your time walking down the aisle.
When you are walking down the aisle, everyone is looking at you, which makes most people a little nervous and causes them to walk faster. By slowing down and making sure there is adequate room between each person will allow your wedding photographer to take a couple of images of each person and make sure they all look great.
2. Have your officiant announce for everyone to be seated.
When the bride walks down the aisle, everyone will stand up. Once she reaches the altar everyone should sit back down, however, that doesn't always happen. If everyone doesn't sit down it can make the ceremony hard to photograph because everyone will be blocking the view of the bride and groom! Once the bride arrives at the altar have the officiant announce that everyone can be seated. This will let everyone be comfortable and will let your photographer have a clear view.
3. Try to stand in the center.
This one is hard to do, I know, and if you and your spouse are off center it's not a huge deal. However, when the couple are at the altar, it looks best if they are somewhat centered. This also becomes important if you have a small aisle. With a small aisle, if you're not centered then you may be directly in front of one of your guests which will partially block you. To combat this, you can either mark the center with a piece of tape or talk with your officiant and they can gently move you into position.
4. Don't have your back toward your guests.
This happens quite a lot. Couples will stand and face their officiant instead of facing each other. Your guests, and your photographer, want to see your faces. Facing each other instead of your officiant will allow everyone to see your profile and your reactions.
5. Enjoy your first kiss!
You are officially married and get to share your first kiss as husband and wife, savor the moment! Your kiss doesn't need to be an hour long affair but having your first kiss be more than a quick peck will allow your photographer to capture a couple images of this important moment!
6. (Bonus!) Consider an unplugged ceremony.
You want your guests to be present in the moment and enjoy your wedding vows and not to be buried behind their phones, cameras, and ipads. You also don't want your wedding photos to show everyone holding up their devices. By having an unplugged ceremony, you will make sure that everyone is there to experience the moment and not busy trying to capture the perfect image. You hired your wedding photographer for their experience and expertise, leave that in their hands.
If you are not a fan of an unplugged ceremony, have your officiant announce (or write it in your program) for guests to stay in their seat and not to get in the aisle or use flash photography. Far to often shots are ruined because a guest jumped in front of the photographer or because a guest fired off a flash right when the photographer took a photo and overexposed their image. I have heard horror stories about this happening during the first kiss and the photographer had nothing to give the couple except an overexposed image or an image with a guest standing in the way.