Whenever you download applications to install, delete the disk image (.dmg) files.
If you know that you're not going to use those applications, clean up them! Open your Applications folder (with command-shift-A in Finder), drag unused applications to the Trash and then empty the Trash. Your Apple Mac comes with a lot of commercial applications on a trial basis (like Microsoft Office, FileMaker etc.). Empty the trash in iPhoto, iMovie, and Mail too. But this is not the only trash you need to empty. Unless you're unsure of whether you may need a deleted file later, there's no reason to have a Trash brimming with files. The most basic thing is to empty your Trash regularly. There are some tips to clean up your Mac. To clean the Apple Mac hard drive is indeed necessary. While Macs don't have a reputation for crashing, they do have a reputation for getting sluggish when overloaded.
Apple's Mac computers are known for being fast and user-friendly, which makes it easy to stock your Mac hard drive full of photos, music, videos, documents and random files.