Shop at the end of the day: Shop when your child's feet are at their largest (either at the end of the day, or after a run or sporting event).

Measure both feet, standing up: Measure your child's feet when they are standing up bearing their full weight. Measure both feet in case they vary in size. Choose the shoes that fit the larger foot.  

Measure and fit with sports-specific socks. Your child should be wearing the specific sock [2] that he will ultimately wear with the shoes. Note: This is a reversal of the normal fitting process in most athletic shoe stores, where socks are purchased as an "add-on" after shoes have been fitted.

Allow for wiggle room: There should be a half-inch from the end of the longest toe to the end of the shoe so that your child is able to wiggle all of her toes. Don't press with your thumb on the greater toe to estimate fit because it activates a reflex that causes your child to curl the bigger toe, giving the wrong impression that there is enough space. In an ideal world, the length of the shoe should exceed the actual length of your child's foot by at least 10 millimeters to ensure that enough space is provided for the greater and lesser toes.

Lace the shoes properly: For maximum support, use the top eyelet on the shoe and run the laces through twice for a snugger fit. Don't tie the laces too tightly, as that can cause injury to nerves and tendons on the top of the foot.

Check for snug heels: If the heels don't fit snuggly, they will pull up out of the shoe (pistoning) and your child will be more likely to get blisters.

Have you child walk in the shoes: Allow your child some time to walk around the store in the shoes and ask them how the shoes feel. When she takes them off, check her feet for any red spots or areas of irritation. Inspect the inside of the shoe for any extra material, glue or irregular stitching, which may cause chafing.

Expect immediate comfort: Most importantly, the shoes should be comfortable right away. Shoes shouldn't need to be "broken in" to feel right.