What direction should a child car seat face?

This would depend on the age of your child.

All children should ride rear-facing in back seats until they are 2 years of age or until they reach the height and weight limit of their child restraints. When children reach the height and weight limits of their infant seats, they should be moved to convertible seats, but should continue to ride rear-facing for as long as possible.

However, when your child reaches the rear-facing height and weight limit of their child restraint, they should be turned forward-facing in a convertible or another forward-facing child restraint.