how to clean up Other folder?

The Other category is not a folder.

See used and available storage space on your Mac, which has this to say about the Other category:

I have this same issue. Roughly 110 Gb is stored on "Other." This is more than all my personal data (pictures, music, documents, email, etc) combined. And I'm reaching the limit of my available 250 Gb storage.

I tried Apple support and the person I spoke with wasn't much help. Then I tried making hidden files visible, checking them out, and discovered that the Library folder in my Home/Username folder had over 100 Gb. So my question to Apple support is, how can I identify which of the files in this Library folder need to be kept, and which can be removed?