Usually, Macs come with not really big HDD or SSD drives, and sometimes you might need this space. I recently had problems with this, where my 500Gb SSD came to a point that there were around 10Gb free.
First, i would recommend you to use some app that will tell you which folders take most space. For this, i recommend DaisyDisk, it costs 10$ but trust me, it is wonderful tool. With DaisyDisk, you will see what takes most space, where to find it, and you decide if you want to delete it.
I discovered that i have a lot downloaded files, some that take a lot space, so i removed most of them. This released me some 3-4Gb. Not too much.
Then i discovered Cache files that some apps create (ex. Adobe Premiere, After Effects etc), from projects and videos i have created. To clean them, do this:
Preferences > Media and click Clean:
For After Effects:
Preferences > Media & Disk Cache and click Empty Disk Cache and Clean Database And Cache
These steps gave me around 20Gb more space.
Next, i have 2 Virtual Machines (Windows 10 & Windows 7), running on VMWare Fusion 8.5. This is the biggest space eater for me. Both take totally 150Gb (each around 75Gb). What is tricky here, you have to follow these steps, in order to squeeze out some serious space from there:
1. Start up each virtual Windows (since both are Windows, its one tool to clean space there: Disk Cleanup) and select all that you want to delete. Its really important to also select Clean up system files, and select old windows installations, and Temp files. This is what i had freed up for each machine:
2. Next, shut down the Virtual machines, and for each one, go to
Settings > General
Clean up Virtual Machine to remove the Reclaimable space:
Voila, i freed me up total of 100Gb space. Next, i will try to move all software tools from my older Windows 7 to the Windows 10 one, and delete that virtual machine, which would give me even more space.