From Writers Helping Writers:
Before Your Edit
1. Agreements about the business details of your project protect you both. An agreement needn’t be a formal printed contract signed in person; an email constitutes a legal agreement. The agreement should define the scope of work, start and finish dates and other relevant deadlines, total cost and payment schedule, and a clear explanation of what happens if either party cancels or breaches the agreement.
2. New writers often mistakenly believe they need a nondisclosure agreement (NDA) to protect their material. Your work is legally copyrighted the moment you commit it to print, making NDAs cumbersome, unnecessary, and often a sign of professional mistrust.
3. Most editors require a deposit to get your book on their calendar, customarily ranging from a flat fee of $100 or more to the first half of the total fee. You can expect to pay your total editing bill in full before the editor releases the edited manuscript.
4. If you can’t or don’t want to use your editor’s preferred payment method, aren’t located in the same country as they are, or prefer a slow payment method like personal checks, ask if your choice will create any issues. Allow enough time to process payments without holding up the project.
5. Missing your editing date by even a day or two could leave your manuscript without time to fit into its scheduled slot, if the deadline is tight or your editor is busy. Communicate as soon as you suspect you may have a problem hitting your scheduled editing date.
6. The time it takes to edit a manuscript varies widely, depending on your manuscript’s needs, the type of editing, and the editor’s schedule and work practices. Developmental editing usually takes the longest. Line editing is slower than copyediting, and proofreading is the fastest editing service.
If there were such a thing as a typical editing rate among all these levels of service, it might run from 20,000 to 35,000 words per week. You get what you pay for. If all the editor has time for is a breakneck race through the manuscript, that’s precisely what you’ll get.
Link to the rest at Writers Helping Writers