I'm on a number of writing forums and one of the complaints I hear most often is about how hard it is to revise. (Yeah, okay -- I'm the one doing most of the complaining.) Feedback from betas and CPs is a great way to start. They let you know the 'big picture' errors and can find those niggling writing habits you aren't even aware of. But when you look at the entire ms, it seems like you'll never get through it. Here are some steps to help you.
1. Yes, revisions are harder than the Twelve Trials of Hercules, so just suck it up and get started.
2. MAKE A COPY OF THE ORIGINAL MS AND EDIT ON THAT ONE ONLY. Put the original in another folder in case you need to go back to it.
3. If there are any big problems (plot holes, missing scenes, character-arc catastrophes), hash those out first, figure out where they'll go in the ms, and write rough drafts of the fixes using a different color-font.
4. Start on Ch 1, read through your beta/CP notes, and rewrite as you go. It's hard to kill your darlings, so don't force yourself to make big changes at first if it doesn't feel right.
5. When working on a chapter, don't try to fix everything at once. Divide up what you need to do into stages, like cutting excess description first. When that's done, go back and get rid of cliched prose. After that, concentrate on the voice (or whatever your weaknesses are.)
6. At some point, this chapter will become your worst enemy and you'll contemplate deleting the whole wretched thing. When you find your finger hovering over the delete button -- GO ON to the next chapter or go watch TV. This stage of the revision is completed if you want to keep your sanity.
7. When you reach the end of the ms, celebrate, eat cake, and crow in all your forums! You did it!
8. Now, go back to Ch 1 and begin it all again.