Here’s what I do especially in sandboxes for rman configurations – backups to disk.

First line – defaults all backups of all types to disk.
Second line – backs up the control file automatically when other backups take place.
Third line – defines where control file backups go and what format the file is in
Fourth line – Configures channel device – file path and file format – this is how you set the default path and format of all backups to disk – except control files – e.g when ever a channel gets used these are the defaults – including implicitly channel usage
Fifth line – tell rman how long to keep records in the control file
Sixth line – tell rman how long to keep archivelog
Seventh line – tell rman how many channels to automatically allocate during a backup – if not explicit in a run block

1.) CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
 2.) CONFIGURE CONTROLFILE AUTOBACKUP ON;
 3.) CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '/oracle/odump/ggtarget/%F';
 4.) CONFIGURE CHANNEL DEVICE TYPE DISK FORMAT '/oracle/odump/ggtarget/%U';
 ...
 5.) CONFIGURE RMAN OUTPUT TO KEEP FOR 7 DAYS; # default
 6.) CONFIGURE ARCHIVELOG DELETION POLICY TO APPLIED ON STANDBY;
 7.) CONFIGURE DEVICE TYPE DISK PARALLELISM 2 BACKUP TYPE TO BACKUPSET;