Never label clothing, backpacks, or personal items with your child's name or any personal information. A stranger can use such information to gain your child's trust by pretending to know them.
Put a system in place for what to do if your child is lost or separated from you in a public place. Practice what they should do in different situations. When you're out with your children, point out safe adults they could approach if they were in trouble, like police officers and firefighters.
Know where your child is at all times. Every parent and grandparent knows how tough it is to keep up with active kids, but having a list of their activities can help. Keep track of their schedule changes, and a list of addresses and phone numbers of places they frequent that you can access quickly.
Remember to update your child's records every few months. Kids grow quickly, and even small changes in height, weight, even hair styles, can significantly alter their appearance. Make sure you have easy access to recent photos of your child, no more than a few months old.