People talk about not knowing how to find a good editor, but when pressed for more detail, they usually don’t have any facts to back up this claim. Mostly, I hear, “they’re so expensive!” without the writer having obtained any quotes, or “I don’t know if they’re good or not” without having looked at any of the editor’s work.
One of the best ways to determine if an editor is qualified is to ask for an evaluation of a small portion of your work. I have yet to talk to an editor who won’t do a free sample edit on 2000-3000 words of your manuscript. Not only does this help the writer to decide whether a particular editor knows his stuff, but it also enables the editor to provide a price quote, based on the level of edits needed.
I always recommend getting sample edits from at least three to five editors. Ask others who they’ve used and how satisfied they were with the level of service provided, narrow it down to five people, and ask. Each one should do roughly the same job, depending on what you’re looking for. If you only want a proofreader, one editor can do that, but another may make additional suggestions as to sentence structure if your manuscript needs help. Prices vary, but a variety of evals will help you determine what fits best in your budget and revision needs.