As an editor, I echo the suggestions for quality editing and beta readers prior to publication. As a writer, I know it takes more than one set of eyes to catch, not only grammatical mistakes, but content issues. Every editor has blind spots--mine being the bottom of the page. Every writer is often too blinded by their shimmering words to see their glaring own errors. That's why this editor-writer plans to rely on the eyes of others rather than only her own myopic ones.

http://www.selfpublishingreview.com/2014/05/why-hiring-an-editor-for-your-book-is-unavoidable/