Go2Linux posted a guide about how to list or find the largest files and directories-folder
When you are running out of disk space, you need to concentrate on the biggest files and folders on your disk, so you can get space quickly.How to list or find the largest files and directories-folders, Free disk space
The best way, is to list the first 10 folders, then go inside some of them, and find files you may or can delete, and get new free space.