The catagory "other" is one of the worst things that Apple ever produced.
I suggest you use OmniDiskSweeper. It will tell you the names of the files and folders that are using the most space on your disk. With that knowledge then you can make the decision as to which files and folders must be moved and which can be deleted.
Hard Drive full or near full?
If your Mac is running a fairly recent version of OS X, here are some general guidelines.
Follow some of my tips for cleaning out, deleting and archiving data from your Mac's internal hard drive.
Have you emptied your iMac's Trash icon in the Dock?
If you use iPhoto, iPhoto has its own trash that needs to be emptied, also.
If you use Apple Mail app, Apple Mail also has its own trash area that needs to be emptied, too!
Other things you can do to gain space.
Delete any old or no longer needed emails and/or archive to disc, flash drives or external hard drive, older emails you want to save.
Look through your Documents folder and delete any type of old useless type files like "Read Me" type files.
Again, archive to disc, flash drives, ext. hard drives or delete any old documents you no longer use or immediately need.
Download an app called OnyX for your version of OS X.
When you install and launch it, let it do all of its automatic test, then go to the cleaning and maintenance tabs and look for the tabs that Let OnyX clean out all web browser cache files, web browser histories, system cache files, delete old error log files.
Typically, iTunes and iPhoto libraries are the biggest users of HD space.
You may have to Purchase an external FireWire or Thunderbolt hard drive to move these files/data off of your internal drive to the external hard drive and deleted off of the internal hard drive.
If you have any other large folders of personal data or projects, these should be archived or moved, also, to the optical discs, flash drives or external hard drive and then either archived to disc and/or deleted off your internal hard drive.
the "other" category in the apple HD storage contains items such as ios device backups, items in the updates and downloads folder, the trash can, etc.
sometimes the mail folder in the user library can be the source of the "other" data. i would recommend getting info on your mail folder to see how large it is and if so you may need to go through it and delete recovered messages that may be contained inside.
also it may be necessary to reindex the HD so it recalculates what's contained on it, the following article tells how to do this using the spotlight feature: