You need to understand two things:
What is taking over space.
Which things are often safely removed.
What is usurping space?:
There are some apps which show a graphical map of disc space, allowing you to rapidly identify where space is employed. i take advantage of one called Mac Optimizer Pro, The results are often surprising, and counter intuitive. A folder with 100 documents might somewhat be smaller than one movie.
What am i able to safely remove?:
If you discover a folder stuffed with movies, which you don’t need, then you'll be able to delete them. But the system often creates caches and copies which are less obvious. as an example iTunes backups of iOS devices are very large, but are often safely deleted (providing you don’t need them).
If you discover a mysterious huge folder, it’s a decent idea to appear online to seek out out what it does and establish whether it will be safely deleted.
The iPhoto and iTunes libraries are often big space hogs. you'll be able to move these to a different drive and release the space. i've got a NiftyDrive installed within the compact-flash slot. it's a 128GB drive in it, which hosts my photo and iTunes library."