Remember back in the day when an 8GB hard drive seemed so excessive? Well maybe you're not as old as me... but I think the trend is a universal one: today's luxuriantly sized storage drives are tomorrow's cramped repositories. Part of this phenomenon is the increasing requirements of the operating systems and programs that we use; as they get fancier, they need more space to run. And the other part is human nature. Nature abhors a vacuum. There is comfort in having five years worth of family photos backed up on your hard drive in addition to your online storage. And services like Google Drive and Dropbox, where files are shared online but also synced to your hard drive, don't help your storage use.
First and foremost, where do you go to see how much free space you have? Go to the Apple menu and select "About This Mac." Click on the "Storage" tab at the top of the window. (This screen shot is from OS X Yosemite - your mileage may vary.)
This gives you a rough idea of what's eating your disk space up. Audio, movies and photos are usually the likeliest suspects for home computers. That "other" category though includes your documents and files (think Google Drive sync folder), trash can, and downloads. That's a lot.
So when the eventual time comes that you are presented with an error that you are out of storage space, here are some tips on where to go to free some of that space up.
1) Empty the trash. Right-click (two-finger click) on your trash can and select "Empty Trash".
2) Look in your downloads folder. Sort the flies by size and see what big items in there can be deleted.
3) See what is syncing in your Google Drive and Dropbox. You can add shared folders into your own drive that syncs, and while this is very easy to access, it does open the possibility of other dropping large files into the shared folder, which then gets synced to your hard drive. You can right-click on any folder and choose "Get Info" to see how much space it uses.
4) Check your documents folder
5) Check iTunes downloads and backups. See this article: http://www.imore.com/how-reclaim-lost-gigabytes-hard-drive-space-itunes
6) Consider getting a utility that will break down in more detail the space you are using. Here are some good suggestions: http://www.imore.com/how-find-out-whats-eating-space-your-macs-hard-drive
7) Check Time Machine - If you enabled Time Machine for backup, it continues to take daily and weekly snapshots, saving them to your local disk. (In the image above, you will see "Backup" and the amount of space it occupies.) Plug in your Time Machine drive to free this space. With many of our systems online and with plenty of storage available in Google Drive, you might choose to turn Time Machine off. Choose wisely! See this article: https://support.apple.com/en-us/HT204015
If you have tried these things and you find that space is still a problem, stop on down to IT and we will puzzle over it with you. We can also back up your important files and wipe your drive to give you a clean start.