Rsync with crontab is pretty simple. The syntax for cron jobs are minute, hour, day of month, day of week and then the command. So in the following the first entry runs at 3:00 pm (1500) every day of week/month. The last entry dumps the trash folder every Tuesday at 11pm (2300). The rsync is as follows -ar means preserve permissions(a) and recursive (r). --deletes means that files deleted on the source are to be deleted on the backup too.
Cerberus :: ~ » crontab -l
00 15 * * * rsync -ar --delete /Various/comhack/Downloads /Various/comhack/Miscellaenous /Various/comhack/Pictures /Various/comhack/scripts /Various/Music /Backup1/comhack/
00 16 * * * rsync -ar --delete /Various/comhack/Documents /MEDIA/
00 17 * * * rsync -ar --delete /Backup2/Movies/ /Various/Movies/
00 17 * * * rsync -ar /Various/New/Done /Backup1/
00 17 * * * rsync -ar /MEDIA/TV /Backup1/
00 23 * * 2 rm -rvf /home/comhack/.local/share/fff/trash/*
The last entry is because you cannot turn off the trash option in fff yet so I just dump the directory every so often.
You can also set an rsync as a simple daily cron job instead of specifying what day and time: https://wiki.archlinux.org/index.php/Rsync#Automated_backup