How do I free up hard drive space?

I bought a 250gb MacBook Pro last year and within a few months, I saw that my storage had dropped to 74gb. I called Apple and they walked me through a process that brought me back up to 200gb. There was a "Manage" button to press. If I can be more vague, please let me know.

But if anyone knows what I'm talking about, please help. I've already moved my music to iTunes Match, my non-essential files to iCloud and I'm streaming my photos to the cloud.

I'm down to 130gb of space on my internal drive.