I used to think that the thing I excelled at was writing a good first draft. I've come to know that the thing I really had to learn to love is throwing away that first draft and working instead on rewriting and editing. I don't really get a decent book until after rewriting.
Usually, the first draft is where I discover the story. I don't outline, so everything's still a bit experimental in that first draft. So when it comes time to turning this mess into an actual book, most of what I need to do is pretty major--cut whole chapters, delete entire sections, rearrange everything, etc.
The first step of my editing process: Discover the scenes that I, personally, truly value. I usually make a list of the things I really want to be in the book--this could be individual scenes, or it could be a character's arc, or even a single line (for SHADES OF EARTH, it was actually a blank page). I list out the things that are essential and true to the story that I need to tell.
The next step: Cutting and re-arranging. This is really a two-step process for me. I need to both look at the scenes that aren't in the list I made in the first step, and decide if they are truly essential to the story. If not--cut. But at the same time, I have to figure out the right order for the scenes I want to keep in. You have to spread out the good stuff, and connect it like little bridges from scene to scene. I can't have all the action at the end and nothing in the beginning. I have to reveal things as I go, not all at once.
Really, my editing process is a matter of cutting out the scenes that I care about and piecing them together into a puzzle that makes a book. I'm very brutal in this--I typically have to rewrite the book at least once to get all the pieces together correctly. It is often very frustrating--but also satisfying, when I can make it work, much like the satisfying click of two puzzle pieces snapping together.