After showing a property, as the showing agent, take time to do a thorough walk-through and inspection of the property. Do your best to make sure everything is back in place and returned to original pre-showing condition.
For security reasons, check that windows, doors, and points of access are closed and locked. It is quite common for home buyers to open and close windows to make sure they are all functioning properly.
Leaving a property in the same or even better condition as prior to your arrival is always a good practice!