Just carve away until you hit bone. Then stop.

Think writing is hard? Try rewriting. 

Here, author Garth Greenwell describes beating his novel into shape:

...My editor, Mitzi Angel, lavished attention and care on the manuscript. She worked by hand, sending me scans of the pages with her markings; a new batch would arrive every few days. As soon as I got pages, I found I couldn’t do anything but work on them, often for ten hours a day.

I worked by hand on a clean copy of the manuscript, with Mitzi’s marked copy on my iPad. All of the changes were at line level, none affected plot or structure, but they added up to a major edit: we cut 17,000 words from an 83,000-word manuscript. Sometimes entire passages were struck, sometimes whole pages; often there would be a note telling me to condense several paragraphs to one. Mitzi seldom suggested particular language to fix problems, but she was eagle-eyed in spotting them. Painfully often, in the margins I found the notation “not good enough,” or “this needs to be better.”

I wasn’t sure I could make it better, and as we inched our way forward I felt I was losing my ability to make my own judgments, or my ability to see the manuscript at all. As I worked through each page I laid it face down, using the overleaf for rewrites, adding scraps and post-its as necessary. But slowly, revision came to feel more and more like composition, and the manuscript came to resemble the notebooks in which I wrote the first draft of the novel. The book, sections of which I had finished years before, became alive for me again.

I hardly saw Madrid at all that summer. I met Luis for dinner every evening, but my days were solitary.