Only take photos at a funeral if the family requests photography or gives permission. Avoid using flash, and try to move throughout the room discretely and respectfully. Give those in mourning plenty of space and sensitivity, and avoid noisy disruptions such as loud directives and fumbling with gear. Unless you are the designated photographer, avoid taking photos at a funeral.
Clarify what the family wants from the photos before the funeral. Determine whether they want photos of certain moments or people, and establish where they would or would not like you to photograph them. Take this into careful consideration while circulating through the memorial service. Ask permission before taking photos of individuals, especially when shooting portraits.
Take a discrete approach when photographing a funeral. It is not necessary to only focus on the family and guests, and try to use the photos to tell the story. Don't use a flash, and make sure to keep your voice down at a soft register to avoid drawing attention to yourself. In general, if the family would like group photos of themselves, a good time to do this is before guests arrive. During the memorial, try to restrict additional group shots to outside or after the memorial service.