Having selected the single-user mode at the start up dialogue accept the shell by 'return' key.
If you get continuous repeated message appearing (mouse for instance) just detach the item if possible.
As the console is all you get (there are no virtual consoles) this is where we enter commands.
To get the file systems up and available and get you to your home folder (me)...
mount -urw /
mount -a -t zfs
zfs mount -a
cd /home/me
Now you have access to the files that are on your system. List the directories with any of these commands.
ls
ls -1
ls -l
Navigate example: To get to your downloads folder use the the command
cd Downloads
To go back a level
cd ..
Plug in a usb (ntfs in this example) so you have a place to save data to and enter these commands:
kldload fusefs
ntfs-3g /dev/da0 /media/da0
Now you may copy files or folders to /media/da0 with commands such as
cp -r Downloads /media/da0
cp filename /media/da0/filename
To dismount the usb enter the command:
umount /media/da0
To remount is use
ntfs-3g /dev/da0 /media/da0
To leave single user mode enter
exit
Posted by a Dummie who had to retrieve his files recently. This is what worked for me.