Difficult to help as you don't say what your OS is ?
In general you'll need to :-
*Ensure database(s) are up,
*Listener(s) are up
*Periodically check that databases are available to users
*Backups ie: Overnight / Archive Logs / Cold or Hot Backups
*Failover methods if the DB does die or m/c goes bang.
It all depends how your company / business works and how much
they need that database. Many of the above tasks can be automated to tell you the instant a problem occurs.
You can use the Ent Manager GUI and scheduled Jobs within this
If using Unix then use crons and shell or Perl.
If using Windoze then Perl and/or Batch files.