Choosing an editor
Choosing an editor can be tricky. Sometimes, you just end up with whoever is cheapest or whoever you know. But if you have a choice in the matter, consider it carefully.
It’s a business relationship like any other
Do yourself a favor, and write a contract. This is a sample copyediting contract, and it’s pretty good. Be sure to change the contract to indicate the laws of your state apply, and clarify it is editing rather than copyediting you are contracting for (unless you are also contracting for copyediting services, naturally).
Working with an editor
Be your courteous and professional self. Editors are a more professional group than beta readers (what I mean is, this is a profession, whereas beta reading is for free and is not a paying gig) and are generally people you hire. They will do copy editing, where they check for typos, etc., although there should be a last pass by a proofreader before publishing, no matter what.
Editors can also check for continuity, but they will mainly read with the audience in mind. They are a good enhancement to the work of a beta reader, and are a good idea before you send your work out for querying.
Finding an editor
The best way to get an editor is to do some research. Ask people you know who have been published, including your online friends. An editor no longer has to live in the same city or country as you do. However, you will be best served by someone who is a native speaker of the language your book is written in. Work with the editor on a sample chapter. Do you get along? Are his or her suggestions reasonable? Are they slow? Does it seem to cost too much for what you are getting?
Finding an editor on a budget
If you are absolutely, utterly stuck for funds, try a local college or university. You might be able to get an English major to help you, but be aware they probably won’t have experience and they may not be the best fit. But they may be all you’ve got.
If you go the collegiate route, don’t just put up flyers. Instead, talk to a professor! Ask who the best students are. The professor may have an idea of who (a) knows what they are talking about and (b) is looking to make some money.
Helping the editor
No matter how much you spend for editing services, be sure to recommend that person wherever they wish, whether it is on LinkedIn, Yelp, or elsewhere. Be kind and helpful to this person, and you could start a lasting professional relationship that will benefit both of you for, potentially, years to come.