Of all the parts of self-publishing that authors should get help with, editing will be your first priority. You don’t have to pay a professional editor, but you do need your book looked at by someone who can be dispassionate and knows their way around a style guide such as the Chicago Manual of Style or the AP Stylebook. This well-written article explores the common myths and the key truths about book editing and editors. Use a wise eye and a cool head to glean what it offers.
Source: 7 Deadly Myths and 3 Inspired Truths About Book Editing