Alana Williams has a short (but succinct) piece on integrating critique suggestions and other editorial feedback into your manuscript over on Cheeky Reads - check it out HERE. (
Link for the Facebook repost: http://cheekyreads.blogspot.com/2011/03/integrating-feedback-into-your-writing.html).
Sometimes, it's helpful for me just to set a manuscript aside for awhile. Let it percolate. Read it some months later with a fresh eye. Sometimes, the project will not see the light of day. I take what I've learned and move on. Sometimes, I'll go forward with the project after time has passed.
And I think that it's also helpful to develop a small network of folks who are able to act as crit partners. People who will be honest, who understand my genre. Folks who aren't afraid to scribble in the margins: "What the hell is this platypus doing here? And when did he learn to play the kazoo?"
I've been part of Columbus Writeshop, a monthly writer's group, for several years. Everyone in our group had to audition to participate, and are either published authors, or are preparing manuscripts, month-in, month-out, for submission to publishers. Both my novels were critiqued by the group, and I got invaluable feedback as a result.