I'm going to take a different approach: What do you want this editor to do for you?
If it's clean up your manuscript for spelling, grammar, etc., you can do this yourself. There is spell check and there are the eyes in your head. If spelling is not your forte, well, no one said you have to read through the book chronologically in order to catch spelling errors. Grammar... maybe some of that's the voice of your character. If your grammar's hideous, you need to learn how to make it not hideous. You don't want to submit an error-riddled manuscript, but, as many people acknowledge, writers are not editors, and no one expects you to be. That shouldn't dissuade you from polishing the manuscript. You can see errors better when you've had time away from the material - become less familiar with it; print it out; and things start to jump out at you. As a writer, these are good exercises that will help you become a better writer.
If you're looking for an editor to advise you on story points - characterization, plot holes - good beta readers can help. Barring good beta readers, you can see plot holes and other issues better when you've had time away from the material - become less familiar with it; print it out; and be very critical. Keep in mind: Does this make sense? Is it too easy? List all the plot dots and make sure they get connected. This approach can also help you become a better writer, but it's a developed skill. Not everyone can read critically in a way we often want from betas, and it's even harder to do when it's your own work.
I see no reason not to try the above on your own manuscript because, in the end, you will benefit as a writer from the skills you develop in the process. That said, if you really want an editor to do it for you, be very clear on what you want. It's your money.