STEP 2: cd to the parent director where you want to check the sizes and run the following command:
mac-book-pro: $ cd /Users mac-book-pro:Users $ sudo gdu --max-depth=1 . 2>/dev/null | sort -rn 309957188 . 198188532 ./sammy 90078488 ./Shared 21678284 ./bobby 6956 ./special1 4920 ./special2
And then you can just keep repeating the process to figure out where all your diskspace is being spent.