Before doing anything, notify the police about the found item. If found at a hotel or store, alert the manager, just in case.
1. Press the home button to see if there's any ICE (In Case of an Emergency) information on the lock screen.
2. If the iPhone is unlocked, check the contacts for ICE information or listings for mom, dad, son, daughter, wife, etcetera.
3. Notify the wireless carrier of the device to see if they can do anything from their end.