I spend a lot of time encouraging writers to reach into their hearts and get out of their heads (those inner critics are serious assholes). Only, there does come a time to unleash your intellect. That time is called revision.
These are my own tried and true techniques for revising without getting overwhelmed.
Let it age: When you’re in the thick of a story, it can be near impossible to see what is and isn’t working. That scene you’re sick to death of might be brilliant, or your clever argument might not even make sense. Resist the urge to pitch or publish a story until you’ve had at least a day, preferably a week away from it. You’d be surprised how much more objective you can be with fresh eyes. If you have a deadline, do whatever you can to add in a buffer period.
In the words of my mentor, Mark Haskell Smith, "Don’t be a feedback bitch": If you think your work is perfect as is, well, you’re wrong. But you also don't need to make every change someone suggests. Critique partners, beta readers, whatever you call them, can keep you writing in circles forever. It will probably take some time, but aim to develop a sense of when to take suggestions, when to politely discard them, and when to use them as a jumping off point for your own solution. My best advice is to be open, experiment with as many suggestions as you can, but save every draft so you can always go back.
Sleep on it: Good, thorough feedback is a godsend, but it can also be difficult to swallow. I've learned that my first response is usually "Holy $%^&, how in the world can I do all of the things this person is suggesting?! It's all just too much!" Then the next day, I reread the notes and find myself nodding along. Sometimes, a challenge that seems like it will unravel an entire book, turns out to be fixable in a few lines. Now that I know my pattern, I don't stress over that initial reaction.
Think Triage: I went to a fiction workshop with legendary editor Sol Stein and never forgot his triage approach to editing, which I use for both my fiction and journalism. The basic idea is that you don’t want to waste time polishing the nitty gritty until you know the piece as a whole works. Start with the big ideas, the characters, the structure, and then get down to precise word choice and comma policing.
Print it out: Ever notice how many errors there are in web articles? The writer didn’t. It’s so much harder to see your own mistakes on a screen. It drives me up a wall, but every single time I print out what I think is already perfect, I find typos.
Read it out loud: Similarly, it’s so easy to skim over a mistake when you’re reading in your head and you know what it’s supposed to say. Reading out loud forces you to slow down so you’re more likely to notice typos, and you’re also more likely to hear weak spots in your prose.