Google for linux/unix system administration will be a good idea. But here I tell you some tips.
1. Try to never use root password to do sysadmin tasks. Instead create a special account for every task.
2. Implement the use of sudo command, read about sudoers file to see the potencial of sudo command.
3. Create groups of users, groups of commands and aliases into sudoers file and grant access using it. This way any command that is not in the file will be not available to the users.
Hope it helps.