I recently took a writing class where the instructor spent a great deal of time and energy trying to get one very important point or lesson across: your first draft will suck!
At first, I shook my head, thinking no way could I possibly let my first draft suck (the idea piqued my OCD behavior tendencies!). I'm one of those writers who edits as she goes. While it's not exactly a bad thing to do, it does slow down the process and "talks over" the creative voice.
The best advice I got from the class was to let myself "write badly", knowing I will most definitely be writing several more drafts following (my favorite part of the process, oddly enough).
Changing any habit is tough, and this has been no exception. I still try to edit as I write my first draft, but now that I'm aware of what I'm doing, I can hush the editor voice and let the creative voice rise.
I still stop about 1/4 of the way through and start from the beginning again, editing just enough to get a better and stronger grasp on where my story is going, who the characters are in all their glory and yes, correcting any issues I find along the way. This process works great . . . for me. I think of it as catching my breath part way through the course before hiking up the remainder of the hill.
If you don't already keep your inner editor at bay during the first draft, give it a try. It's very freeing! And it allows the creative voice to pave the way.
Here is a link to an informative and entertainingly written guest column on the Writer's Digest website by author Kathy Leonard Czepiel. - http://www.writersdigest.com/editor-blogs/guide-to-literary-agents/5-tips-on-writing-first-drafts
Enjoy and good luck with your own process!