Let's cut to the chase. You have editing to do. So do I, and the quicker I slap these tips on the table, the quicker I can get back at it. I've gathered this advice from other writers, from beta readers and from reading. These tips are good, but that doesn't mean they're absolute. Find your writing voice, and balance it with these - you don't have to, of course.
But you should.
1. Revise before you edit.
Don't line-edit on your first go. It'll waste time. When your project is finished, look at the entire thing from a distance, ignoring all the little grammar errors or dialogue you want to rearrange. That's for later. The first step is to look at your glorious mess of a first draft and find the spark, the part of the book that carries the entire story's spirit with it (aka the reason you started writing it in the first place). Once you've identified the spark, compare it to your plot. Did the rising action do what you wanted it to? Did the climax take the story where it needed to go? Is the ending actually good? If not, how can you fix it? If yes, how can you make it better? Ask big questions and make big changes. Invert the whole thing if you have to. Revise first.
2. Get feedback and use it.
Find people you trust who also meet some other qualifications, such as reading in the genre you write, or being writers themselves. It's fine to have that one person who will never give you criticism (for your sanity's sake), but be on the lookout for constructive feedback. It will hurt, because it's impossible to be a writer without feeling like you've just been slapped most of the time, but you will improve. And nobody's forcing you to take every suggestion to heart. Listen to the feedback with humility, and then make wise, story-centric decisions based on what you hear. Other people are a valuable resource, so don't try and write a masterpiece by yourself.
3. Be ruthless. (Cut!)
Delete anything that doesn't contribute.
No, wait. Don't misunderstand me.
I said anything.
If it doesn't move the plot, if it doesn't characterize, if it doesn't serve a real purpose - cut it. This will most certainly sting. But after doing it for months now, I've actually gotten to the point where I'm enjoying it because I can see immediate improvement. I know my plot so well that I can determine whether or not that conversation really needs to happen, and once I remove it, the scene sprints instead of limps. Cutting unnecessary junk streamlines your writing and gets readers to the point - which, given the literary climate these days, is a pretty darn good thing.
4. Set an end goal.
If you're like me, you're likely to get sidetracked and end up working on one project over the course of 4 years without any kind of set structure. I recently decided to finish this draft by March and start querying by the end of the summer at the very latest, and it's given me new fire (mostly because deadlines are like speeding, fiery, explosive trains). End goals have reminded me of the big picture, and now I want it more than ever, so it's time to make it happen - starting with setting an end goal. Give yourself a deadline if that helps, or just set a general goal, big or small. Every accomplishment is still an accomplishment.
Next week, I'll go over some smaller, nitty-grittier editing tips, but for now, use these. Think master-plan. A book is way more than just a collection of chapters: it's a whole. If you ever feel too swamped by the details, then step back, for goodness sake. Like I said earlier, the spark, the reason you started in the first place, is your motive. Don't forget why you started.
Okay, that's all. Go write!