During using, both users and even Mac OS X generate and accumulate too many unnecessary Data (image, File, Cache,…). Look at the following tips to manually free up a ton of space from your Mac HDD in Mac OS X.
How to check how much much disk space has been used and still available in Mac OS X?
Access Disk Utility (Found in Finder/Applications/Utilities/Disk Utility), then select the Info tab.
Remove Files and Folder you do not need, empty the trash
You may want to delete old data generated by apps: iPhoto, iMovie and Mail. So you may want to empty their own trash too.
Mail: Mailbox > Erase Deleted Items > In All Accounts, and Mailbox > Erase Junk Mail. (instead of deleting, you may also consider archiving your email, see #6: Compress your items below)
iPhoto: iPhoto > Empty iPhoto Trash.
iMovie: File > Move to Trash or File > Move Rejected Clips to Trash.
Delete Apps no longer used
Empty Download Folder
Clean up Safari’s History
Click on Safari at the top menu —> Clear History.
You might find the right way to deal with other Browsers (Firefox, Chrome,…)
Storage large Files in External HDD
Move Data to an External Hard Driver is absolutely a good solution.