The National Center for Missing and Exploited children recommends that the photo should be a portrait of your child that faces them square on, from the shoulders up (think of a school photo when taking it). Make sure that the lighting and backdrop afford the clearest view of your child's features. Write the date of the photo along their name and details on the back and place it in your wallet. In six months, take a new photo.

This method might work well if you have one or two children....but if you have a bustling household, photo space in your wallet is likely already a precious commodity. Consider making single-sided child ID cards with an economy ID printer like the Zebra p110i. A single-sided card is inexpensive, and can hold all the details of the photo, but with a more durable and portable finish.