Choosing an Editor
You will work closely with your editor. You'll want to consider several things when you choose them.
Can you afford them, not just for this project but also for all your future projects?
You'll get the best editing from someone you work well with, and the more you work together, the more you'll "get" each other. If your budget is tight, you may not be able to have the same editor project after project as their rates increase. Not a dealbreaker, but if you can start your relationship now, then go for it.
Does your editor offer all the services you want them to?
Some editors offer editing at all stages of your project, others form teams. Others specialize in one of the steps. It's fine if you have different editors for each step (and I would argue that by the time you get to the copyedit step, you need fresh eyes, so a new editor whether it's an independent editor or a member of your editing team who has not read your current work yet). You need to ask yourself if you want a team or to find each step's editor yourself.
Photo of book open with a left and a right page both curved so together they form a heart; fairy lights out of focus in the background.
Photo of some of Penni Askew's resource books standing with spines facing viewer. Chicago Manual of Style, a dictionary, several writing, editing and grammar books.
Do you communicate well with each other?
Depending on which stage of editing we're talking about, the amount of communication back and forth will differ. When you're working with a developmental editor, once they have returned your project, you should be able to ask them questions and have some discussion of pros and cons for if you do this or that. If it's not clear in the contract how much communication is included in the fee you paid, ask. By the copyedit stage, communication should be pretty minimal--updates that your project is going well or questions the CE has. But once they've returned it to you, you shouldn't have very many questions and can accept or reject each change based on your preference.
How will you know if you and your ed make a good team?
You can "test drive" your editor by paying them for a smaller project if you have one. If you only have a full-length story, you can talk with them about providing fewer services (for example, a manuscript evaluation instead of a full developmental edit). For a copyedit, get a sample edit. If you like the sample, then you could hire them for the complete project.