I recommend using treesize. It provides a very intuitive graphical view of the allocation of used space, and makes it easier to track down junk files.
http://www.jam-software.com/treesize_free/?language=EN
PS, keep in mind that with an SSD, you do not need to keep any music or documents on the drive.
They can be relocated to a different drive, and the libraries can be edited to target the secondary drive, thus everything continues to work normally.
For example,
A folder on the 2nd drive can be included.