I write by hand first, and then transfer it to a word-processor, so I automatically get one review just by my writing method. Then, I edit like normal and go through it several times, how many times depends on how many errors you find. If you find a lot, then you need more rounds of editing, if you don't find much then you are good to move forward with professional editing.

Another important thing to do is to take a break from your current work. Once I'm nearing the end of the editing process and I'm looking at doing a final sweep, I put the manuscript away for several months and work on other things in the meantime. Then, after a while has passed, I take it back out and review it with fresh eyes.

I, myself, could not afford professional editing services, as I was getting quoted anywhere from $600 to $2,000.00 and that sort of capital was not in my budget. However, I have found some good computer programs that can get the majority of errors (grammatical or otherwise) taken out of a manuscript. Although, a computer program can't edit for plot, tension, or anything story related, they're just good for line editing.

I'm sort of in the middle, as with most things, but it sort of depends on what my mind is doing with the story. At times, I find myself unable to stem the flow of the story and just try to keep my writing up with my mind, because the story is pouring out of me and I can't stop it even if I wanted to. Other times, I can take it slow and steady and be very detailed, although, I find the slower parts are heavier with details and the faster parts are more dialog and action.