The most efficient way to free up disk space is to delete some large files and folders you no longer need.
Look at the disk map and try to locate unusually large folders. Then drill down and find out what actually takes so much disk space.
iTunes library often take tens or hundreds of gigabytes on users’ disks. Here’re a few suggestions on cleaning it:
Check movie (~/Movies) or music (~/Music) folders for large films, podcasts or music collections you may not need anymore.
Download (~/Downloads) folders are often filled with lots of large useless files. It’s usually a good idea to move everything valuable out of this folder and just empty it from time to time. If you use any file sharing clients, check if you really need to keep all the stuff you download from the net.
Modern games successfully compete with HD movies for taking most of the disk space. Mac App Store or Steam gamers are lucky: they can delete their games and download them later.
Mac App Store games are normally located in your Applications (/Applications) folder and Steam game folder can be found in ~/Library/Application Support/Steam. Just don’t delete Steam games from DaisyDisk, use Steam’s own UI instead.
Some applications leave huge cache files or libraries in ~/Library/Application Support, but be careful when deleting anything from this folder and know what you’re doing. If you need to remove certain application with all of its settings and data, use special tools like AppDelete.