Know the different types of editing, especially if you hire an editor. Otherwise, you may be disappointed or not get your money’s worth. I’m always amazed when I find a multitude of goofs in a book that has supposedly been edited. Just because a person can read, doesn’t mean s/he can edit! Furthermore, if they’re a specific type of editor, they may do a great job in that category, yet leave others flapping in the breeze, waiting for some discriminating reader of jump on them like a duck on a June bug.
Rather than reiterate what has already been said very well by another blogger regarding the different types of editors and what their duties are, check out this outstanding blog.