Smiles take first priority.
Take lots of pictures, in a pinch you can photoshop eyes, or smiles.
Do vertical, and horizon shots, you don’t know what the family may need them for.
Do many different combinations of family members. Dad + Mom, Dad + Girls, Siblings, etc.
Try to get some casual ones of the family interacting.
Do test shots. What I’ll do is as we’re walking to our location I’ll pick one or a couple of the kids and tell them “I need your help to do a test shot”. I use that to get my settings all right. Also it makes the child feel special.
When you’re setting up the main family shot; take your time, checking that you can clearly see everyone’s face.
Photographing family (your own or someone else’s) is a great privilege but also a great responsibility.
-Hannah