It's been one year since my "call" anniversary, and if I had to give one tip that I've learned, it's this: expect revisions, lots of revisions, with every manuscript you turn in. Expect edits, too. Expect never to have all the time that you want to complete everything as well as you'd like to before the deadline is up.
I've learned that the revisions and edits are something to be grateful for, because the story is always better at the end of the editorial process than it was when I turned it in. And if I didn't have deadlines, I might never let the story leave my hard drive. (Sad, but true.)
Now I'm going back into "hermit mode" to finish working on my revisions. Happy writing!