My reputation for writing quickly and effortlessly notwithstanding, I am strongly in favor of intelligent, even fastidious revision, which is, or certainly should be, an art in itself.
As Flannery O'Connor says, a person can choose what she writes but she can't choose what she makes live. Some people are really acoustic writers and so for them the secret revision is sound. Other people may revise in terms of the way a paragraph feels. There's a million ways to do it.
Oh, I've discarded a great many [poems]. And occasionally I've discarded and then resurrected. I would find a crumpled yellow ball of paper in the wastebasket, in the morning, and open it to see what the hell I'd been up to; and occasionally it was something that needed only a very slight change to be brought off, which I'd missed the day before.
There's no reason you shouldn't, as a writer, not be aware of the necessity to revise yourself constantly.
One of the things I like to do during an 'overhaul' revision is bust out my highlighters and colored pens. Tools like these make me feel like a real writer.
I rely heavily on my beta readers' honest critiques.
Then, rising with Aurora's light, The Muse invoked, sit down to write; Blot out, correct, insert, refine, Enlarge, diminish, interline.
Sleep on your writing; take a walk over it; scrutinize it of a morning; review it of an afternoon; digest it after a meal; let it sleep in your drawer a twelvemonth; never venture a whisper about it to your friend, if he be an author especially.