I'd like to reiterate something: not only is it a bad idea to always use root, it's A TERRIBLE one too. Say, you wanted to delete everything on your floppy in root by typing "rm -rf /mnt/floppy" but you accidently press enter when you type the "rm -rf /" part. Kiss your system goodbye, because the essential files are already deleted. I recomment doing this command
echo "alias rm='rm -i'" >> ~/.xinitrc
this will acsk you permission when deleted files.
In addition to su, you could type
su -c "command"
that will do one command after your password and then go back to the normal account
There is also "sudo" but I never bothered to learn it.