Cron job doing VACUUM and BACUP from root

Have been searching around the last two days to find some scripts or
cron jobs to automate backup and vacuum.

I'm running a small db on PSQL 7.02 / RH 7 and keeping my login as
root.

I know how to set up cron from root and I believe it should be
possible to call the job from root, or am I totally wrong. 

For what I have been doing I only get FATAL 1 errors, believe that's
from not being in su postgres ?

Any help and assistance (step by step) to a novice would be helpful. 

Regards,

Aage J. Skjolingstad