Editing--the hardest thing to do for a writer. It seems that no matter how many times you read your book, backwards, forwards, silently or aloud, you always miss a typo or spelling error. I try to read mine aloud because it's a little easier to catch the missed words that way. You know--that to or it that you thought, but didn't type?
I usually set my book aside for at least a week, possibly even two weeks before starting edits. I find it easier to notice the problem areas with a fresh look. It's easy to get so close to your story that you can't see the trouble spots.
When I'm working on the story, I stop each Monday and take the time to read it from the beginning. That's when I look for continuity problems and time line breaks. That Monday reading has prevented a lot of rewriting because I don't get too far without catching the problem.
All of us have our little tricks when it comes to editing. Some lucky writers have beta readers who read their work. Some have eagle-eyed critique partners who point out problems. Some of us just put our nose to the grindstone and keep typing. Ultimately, we all do whatever we have to do to finish the story.
That's why we're writers.