In order to allow my wife and myself to both have access to our common photo directory, I created a folder called /home/photos and set permissions as follows:

As root, create a new group and add users to it:

addgroup photos
adduser user1
adduser user2

Create the folder:

mkdir /home/photos

Set the group:

chown root:photos /home/photos

Set the permissions:

chmod g+rwx /home/photos
chmod a+s /home/photos

The last command sets the setgid bit so that all subfolders and files will inherit the photos group.