Editing, how to do it and do it effectively? That is a good question. I'll give you my opinion. I won't keep saying in every sentence that it is. Some people will disagree. That's fine. This is how I feel it should be done.
A lot of people will tell you to set aside a novel for six months or some insane (to me) amount of time so that you can look at it with "fresh eyes". Well, this doesn't work. Believe me. You will never ever have truly fresh eyes for your own work. It will always be yours. It's like saying if you haven't seen your own child for a few months, they won't be your child. Setting it aside for a short time isn't a bad idea, but don't think that will make you truly see it as though you haven't seen it before. You wrote the sucker. Let's be real here.
However, there are a few tricks that help you really see it. Assuming you write on a computer, first change your font and font size and then print it out. Just looking at it in a new medium with a new appearance helps it seem different. In fact, it helps a lot, well worth the expense of all that ink.
For the first edit, try not to worry about typos. Ok, correct them when you notice them, but there is no point in concentrating on typos that might be edited out anyway, because what you need to concentrate on first is a story-level edit.
Doing this there are several things you need to look at, and I look at them all in the same edit rather than going over the novel once for each issure.
- Conflict. Does at least some conflict start in the first chapter. It doesn't have to be the main conflict, but just telling a reader how cute and charming the main character is or telling their life story from first grade won't likely keep them reading. So present some problem, even a minor one. And bring in at least part of the main conflict soon. And I happen to agree with some people that even in chapters where the conflict is not the main point, the conflict should never be far away. If there is no conflict, what is the story doing? Never lose sight of your conflict.
- Pacing. This is a very tough one for an author to judge because you're probably interested in the most mundane things your character does, but if the story drags the reader is going to notice. Does the conflict get repetitive, for example, with the character solving very similar problems over and over? Does the same situation drag out too long? Or is it too rushed? Oh, this is hard to judge, but an author has to try to see it. (And pacing is one of the reasons I think an editor is essential)
- Character development. Some types of novels and genres tend towards more character development than others, but if your character doesn't change and grow in the course of your story, then you have a problem--a serious one. Many readers will forgive a lot if you have good character development. If your character doesn't develop at all, try to think of them as a real person who needs a little prodding to grow up.
- Point of view. Make sure it is consistent. Keep an eye out for inadvertent head-hops where you suddenly tell what someone is thinking when your PoV character couldn't possibly know.
Once you have the story level edit done, I suggest another read for a copyedit. For this, I read it out loud. That way I have to look at every word. I do this on the computer screen rather than a print copy, so I can immediately make corrections. Once again, I change font and font size to alter the appearance.
I look at this stage for inadvertently repeated words. I tend to suddenly decide to use a certain word several times in a couple of paragraphs. I look for awkward phrasing. Obviously, I look for typos and misspellings.
I don't think that editing over and over is productive use of one's time, and I know a lot of writers who do this. I suspect most authors who do this (my opinion) don't really know at what point they stop making improvements and start changing for the sake of changing something. I'm also not sure they know at what point they start editing out their own voice. Of course, I also edit as I go, so perhaps I cheat a bit. My own opinion is that after you've done the kind of edit I describe, you really need someone else to look at it for you.
Once I've done the editing I described, I send it to an editor. It is extremely difficult for an author to see everything in their own work, and I think a professional set of eyes is required. However, this kind of editing process will send you a long way along the road to a finished manuscript.