I have a rule that I always type in the full path to whatever i'm using 'rm -rf' on.. I'll also preach it to anyone i'm teaching..
IE: if you're root and you are in /home/rob/Downloads/ and want to remove the /home/rob/Downloads/etc/ directory, type in the full path to it.. you don't want to accidently wipe out /etc/
(also, don't run around as root unless you have to!)