Second, consider getting a critique before you decide whether you need to pay for a full copyedit. I (and probably many other editors) will read your manuscript and write a several-page critique for much less than the cost of a line-by-line edit, and if your mechanical skills are reasonably good, this may be sufficient to help you get it into adequate shape for your publication plans.
Software and Systems – Some of us writers like using certain types of writing tools or software.  I personally love to write my books using Scrivener, and will then switch to Google docs for better tracking systems.  However, I've run into editors who only use Word document.  That's no bueno for me.  So, make sure they are good with whatever writing programs you want to use.
It’s always sensible to follow due diligence in submitting your first draft of your book to an editor by making as fool-proof a copy as possible for you because first, it is your own creation, and secondly, a horrid draft sent your editor can end up frustrating both you and him or her. Make your own corrections to the extent you can, so that will make the job of your editor that much lighter and the end result would be a lot more effective.