Don’t do your self-editing all at once, consider a 10-step plan and never filter the action.
As you begin the rewriting process you also begin the editing process. This is the art and the heart of it, this is when you start to build castles, and the rewrites, you can share with your writing group, or your initial reader. A poorly edited manuscript is certain death for any legitimate agent or publisher. In addition, it is one of the things within your power to control along the journey to publication. Do it.