Just write a script that perform the operations you usually do manually, maybe adding some control statements, then insert it in the user's crontab with
"man crontab" and "man 5 crontab" give the general information about crontab and describe the format of the crontab entries, respectively. Before you ask, I can summarize some general rules about crontab jobs:
1. in your script always use full paths for each command. The cron environment is different from what is set-up at user's login (that is you don't have the same environment variables) and PATH is usually limited to /bin:/usr/bin.
2. redirect the standard output and the standard error of the job to a file for easy checking at a later time. If not redirected, take in mind that they are sent to the user's mail by default (check it using the mail
command from a terminal).
3. use full paths for every file name inside your script, too. Independently from where the script is placed, when the job starts it acts as if it run from the user's home directory. Full paths avoid confusion.
And to make things worse it always contains documents that are really needed.
This suggests that a full and regular backup of sensible data/documents is always welcome! Don't wait for things going bad: better to be prepared.