How to find the largest directories or largest files?

A utility called ncdu will give you the information you are looking for.

sudo apt-get install ncdu

On OS X, it can be installed using Homebrew:

brew install ncdu

Following command shows you one level of directories and their sizes

du --max-depth=1 /path | sort -r -k1,1n

If one of them really sticks out (the last one on the list is the largest due to sort -r), then you re-run the command on that directory, and then keep going until you find the offending directory / file.

If all you want is the ten biggest files just do

find /home -type f -exec du -s {} \; | sort -r -k1,1n | head

From any directory:

du -a | sort -n -r