First: leave it alone. For a long time. In fact, if you don't look at it even once for almost eleven months, that's just about perfect.
Then think about all the parts you remember that make you cringe. Resolve to do away with them. Remember how you imagined your novel back when it was something you were excited to start working on.
Next, get notes from a careful reader or editor. Believe them. Compare them to what you already know about problems in the novel. Think carefully about possible solutions.
Last: cut ruthlessly. Experience elation.
I'm kidding about the list (although it doesn't strike me as bad advice), but in my case, this is more or less what has happened. I received my notes from my editor on July 15 (seven single-spaced, 10-point font pages of awesome insight), and after one week of mulling and strategizing here in the city, I took two weeks of vacation in which I planned to make a big push on the edits.
And last night I got home from two wonderful weeks in the country where I had planned to buckle down and edit edit edit like crazy. And editing in this case was going to mean writing whole new sections from scratch, since I decided I wanted to cut about a third of the existing text.
I did a fair chunk, but not enough. There were other commitments and distractions (mostly good ones), and the summer is so short here, I thought I ought to give it its due, which meant hiking up mountains, trips to the water park, stargazing, and cookouts down by the lake. No regrets, but I'm going to have to make a strict plan for how to get through the rest of it.
At the moment, I'm 28,000 words lighter (though this is likely to change), and the novel is finally beginning to be something closer to what I imagined it back in 2007...before I started writing it.