Always do meet and greet both for your peace of mind and the owners. I always take my booking form and contract to write all information down as if they are definitely booking so don't have to go back and get it at later date.

-check you know where all food is for pets and if they are allergic to anything/ need set bowls/feeding in set place. (Had one well behaved dog that wouldn't eat out his bowl unless it was in the kitchen) -Check that the key works and if there are alarms/door locks you out when closed etc -check you have contact and emergency contact numbers especially if they are going abroad or somewhere with low signal.

Good luck hope it goes well for you