I've done four covers through Ebook Launch for two different series, and they've knocked it out of the park every time. In one case they were creating brand new covers based on a high-concept mashup idea. In another, they were following in the footsteps of a different designer, who'd already established the look for an existing series. Both times -- whether coming up with something totally new or sticking to an established style -- they did fantastic work. I love my Ebook Launch covers!
I would add the suggestion to be prepared for the editor to request a look at the manuscript (not just a short sample) to prepare an accurate estimate. This has been my practice for some time, and it allows me to provide a flat fee for the entire project. This makes budgeting much less complicated for the author, although of course I am willing to bill by the hour if preferred.
If a book has an editor, you will be able to find their information in the opening pages of a book before the table of contents or first chapter. This information is often on the copyright information page, although the editor’s name may be listed in the acknowledgements or on the title page instead. If a book has no press or an editor is uncredited, you may need to do some research or contact the author to get editorial information. To contact an editor, contact their publishing company or use their personal or professional website to reach out to them. Remember to always be cordial if you’re planning on a getting a letter or phone call back!
I do developmental editing mostly, so I charge a flat rate to read once and build an action plan, half before and half afterwards. Then we contract to work through the plan, where the bulk of the editing takes place and for this I charge 25% up front, 50% after the developmental edit, and 25% on completion of the final proof. I find that authors appreciate the spread payments and the transparency this brings.
You might hire someone for a proofread, but let the editor know that you’re open to hearing from him or her if the work needs a heavier edit. The editor would need to present you with evidence in the form of sample pages that showcase what’s needed—and your job is to make sure you agree. You want to feel like an editor’s edits are polishing your work and making it shine. If you feel dread or anger, or even if you feel misunderstood, it’s likely not a good fit. At the very least you want to share your reactions with the editor so they can respond or change course.
An edit is a business transaction. This means that money will exchange hands. Therefore, you need to approach the edit as both a writer and a businessperson (an increasingly common role in the age of self-publishing). Compare the deals you’re offered. Editors with brand-name backgrounds might offer less user-friendly terms (such as hourly rates, which are less predictable than fixed contracts), while less established professionals might offer discounts and extras (such as book formatting and publishing consulting). Don’t be afraid to ask. Hiring an editor is a professional investment. A sample edit will allow you to estimate the value of the service, but never forget about the price.
I cannot speak for all editors, of course, but I know I and many of us would be open to editing just part of your book at first, say, a particular chapter or two that you sense needs a lot of work. That is often enough to show you mechanical errors that you tend to make repeatedly. You can then go through the entire manuscript yourself looking for as many of the same kind of errors as possible. You will sharpen your basic writing skills in the process, and it will pay off in all future projects.