It’s a very obvious idea that had never occurred to me until I saw this video.
I have my contact information printed on a label on the back of my iPad, but why not put it right on the lock screen, so anyone who finds my iPad will see who it belongs to as soon as they turn it on? It’s as simple as putting your information on a photo, and making that photo your lock screen photo. You can complete the process with any photo editing program you feel comfortable with, and this author walks you through the entire process.
The video is specific to the iPad, but the same approach would work on any Android device, so long as you have the ability to set your lock screen photo.