9. Let any joey fly the coop whenever they see fit.
8. Then let them come back whenever they decide they're good 'n ready.
7. Allow yawning, sidelong glances and pointing.
6. Use a furry, singing and dancing, santa-cap-wearing bulldog toy as an attention-getter that is 4 feet above the camera lens and is slowly losing battery power.
5. Give your youngest daughter impromptu flamenco dancing lessons AND scream SMILE! so loudly it hurts your son's ears.
4. Scream SMILE NOW OR YOU'RE ALL GETTING A TIME OUT! in such a threatening manner as to make all subjects look confused, coerced or despondent.
3. Expect everyone to look at the camera at the same moment.
2. Incite clapping. (Incitement can include, but is not limited to, actions such as frowning at camera's display screen, saying the word "milk" and the cat meowing in the background.)
And the #1 way not to take a Christmas card photo:
Do NOT Photoshop-merge each subject's most presentable face into one photo as shown below.