Many said that authors make the worst editors. To some extent this is true because reading through my own work, I find it challenging to be 100% objective in judging the piece. It's hard to realize the holes, the missing points when you already know the events happening by heart before even reading them through. I've only gone through the first chapters in the plot and I realized the further you go, the harder it is to maintain objectivity because every line rings a bell. The more lines you read, the more bells it ring. I can't imagine how I will be able to judge my characterization when I already know those characters by heart, as if they were real people standing in front of me right now.
This is exactly why you need to make sure you give enough distance between finishing your draft and starting to edit it. Trust me, a week won't be enough. Spending only a week away from the characters you have grown to love for a year, or maybe two, will not be enough to make you step out of your own story. If you have a deadline, then you have no choice but to work on it as soon as you can. But if you don't, spend weeks away from it, months if you can. I'm not saying don't do anything for months. I'm just saying don't do anything with the draft for months. Work on something else, start a new writing project, whatever it is, keep yourself busy with other writing stuffs so that your mind will be absorbed by something else. This will help you to grow out of your story and build objectivity over it.
Okay, don't get me wrong. Editing isn't as excruciating as it sounds. It's actually kind of fun. You get to read through this thick bundle of pages that you have written and as you go on, you will realize that you can write. I don't know whether you can write well or not, but I'm sure you can write, because you have written that many words on paper and that proves you have something. I mean, you just have to admit that some sentences will blow you away and you'll be like: WOW! Did I really write that? Am I that awesome? But of course, this only applies to "some" sentences, as in a very small number of them, because most of the things you wrote in your first draft will be crap. Now, to turn those crappy sentences to a masterpiece, you need to go through this editing stage. And to complete this stage with style, you need objectivity, lots of it.