Have the photographer peek through the lens for things that might look strange. Another fun way to arrange the family is in front of the Christmas tree, or borrow the wreath from the front door and hang it up as part of the backdrop. Some families wear matching Santa hats. Others opt for a more serious photo, and arrive for the photo shoot in dresses and jackets with ties. Some families like to hold a handmade sign, of course made with colors that coordinate with those in the picture, and show the date on the sign.
Outside pictures are nice, too, especially in climates where there is snow for the holidays.
Make a snowman, and gather the family around it. Decorate a tree for the birds and small wild animals and stand around the tree for your photo. There are endless possibilities for where to take the picture. The most important consideration is that the family looks natural in the photo. There are two options when actually creating a card, if that is part of your plan.