You can’t go wrong with an article like this one by Martha Carlson-Bradley at Editing Queries. I published 3 books without the help of an editor and lived to regret it. I found an editor (a good one, by the way – Jenny Quinlan at Historical Editorial), but I didn’t have access to all the tips given here. With my editor’s help, I revisited the first three, and her editing was invaluable for numbers 4 and 5. My advice is to copy this. Print it. WARNING: Do not, under ANY circumstance, publish without finding a good editor. It’s just as important as your cover, maybe moreso.