In the years I have been writing, I have found how useful criticism can be. I seek it out as I'm writing. But in order to avoid letting a rejection or negative review bring creativity to a halt, as I've done in the past, I've learned that writers must:
1) Look closely at any criticism of their literary efforts,
2) Measure criticsm thoughtfully against their own purposes,
3) Apply what is constructive,
4) Discard all that isn’t constructive,
5) Move on to write again.
It is far better to have written and be criticized, than never to have written at all.
Of course, like many things in life, deflecting critical darts is easier said than done. It has taken me many years to get to the point that I can quite quickly stop the bleeding, step back, and analyze the criticism objectively. It has made my writing better, and I give a lot of credit for the popularity of my stories to my editors. They see things I miss. That doesn't mean they are always right. No one knows the characters, plot, and purpose as well as the writer does, so it is important to keep that purpose in mind and to guage other suggestions and criticisms against it.