Mining for gold
It's difficult to describe what I do when I rewrite. Not one sentence remains the same from first draft to last. Every draft is a different adventure. Often I just don't know what will work for the story until I write it out. In outline it seems like a fine idea--then in practice it just doesn't work. I have to keep reminding myself that no writing is wasted, even if it gets cut. I spend a couple weeks worth of work writing and rewriting a chapter only to cut it. Still, I had to write it in the first place. For some reason, I needed to see it before I knew to get rid of it.
Every writer's process is different. Ann (A.E.) Cannon pointed out that most writers either start with character then find the plot, or start with plot then find the character (and of course it's the combination of those two, character and plot, that make story). I'm the latter most often, starting with plot. Whichever you are, it becomes the work of rewrite to find the other. Those I know who start with character, their rewrites often consist of drastically changing the story to fit the character. On the other hand, the general skeleton of my plots don't change much from first draft to last. The characters change, develop, affect the essence of the story. For example, I'll put an event in the middle of the book in the first draft. That same event will most likely still be in the final draft, but every draft in between, the way I tell it changes, the words, what the character says and does, why the event is important and how it affects the rest of the story.
I don't know that there is one way of writing that's any easier than any other. This is just the way I work.
But know this--all writers, novice or professional, have to get our hands dirty. We have to cut things we love,break things and fix them, tear out scenes and fill the gaping holes,discover new subplots and make them work with the whole. Never, neversay, "That's close enough." Fix it! Change it! Do the dirty work. Getting grimy is the only way to shine.