I ran a free book promotion for Sector Storm, for five days, with 622 copies 'sold' (given away.) Not bad for a beginning and it should help to get my book distributed. I've noticed it's found a lot higher in the searches now.
Midway through the promotion I noticed that I'd overlooked a number of grammar errors and typos. Normally when I'm in the editing phase I'll go over a book several times until I find myself nitpicking; an indication that I'm in overkill. But while working full-time at my night job and having done my 'creative editing,' I felt confident that one thorough review should find any technical mistakes. I was wrong. Lesson learned.
The typos are the trickiest to find; while scanning a page your brain reads the word that you meant to type, not what actually got written: "vehicle" instead of "vessel." This example isn't a big deal, but I'm a perfectionist at heart.