Next, I check their work history to see what kind of projects they have been working on. For example, if I’m hiring an editor and I see that 8 out of their last 10 projects had nothing to do with editing, I will probably pass because it means they either don’t enjoy editing work or they aren’t able to find enough of it on Upwork, which should not be a problem for a highly skilled editor.
The Vietnam war is on and our protagonist (me) joins the Navy to avoid being drafted. Ordered overseas, he loses his respect for the cultural norms of his parents’ generation regarding sex, marriage, and the war. Tom is on a great adventure. He also loses his virginity at the age of 19 while stationed in Korea. The narrative is full of shocking revelations about the conduct of that war along with sweet and very personal vignettes concerning Tom’s personal life (nothing salacious, no titillating descriptions of the passionate and torrid sex which occurred). Stories and pictures relating to women in three countries who competed for Tom’s affection. The epilogue reveals that Tom is still married to the woman that won him 41 years ago. They have four grandchildren today. Tom (me) has a positive outlook throughout, enjoys all the challenges and relationships, and is still convinced he has achieved his life’s goal of being a dependable husband, father and grandfather.
I'd suggest working through each change so you can learn for next time, rather than just clicking Accept All on the Track Changes version. This will take time, but it's well worth it. I usually accept 80-90% of my editor's changes and the manuscript is improved considerably by the experience. After the line edits are updated, I send the manuscript to a proofreader for the final check before publication.
I’d add that for UK writers, the Society for Editors and Proofreaders (SfEP) Directory is the best place to search for editorial professionals. Each editor has been vetted for professional competence through the Society (you have to be assessed to become a Professional Member or Advanced Professional Member), so it’s a pretty trustworthy source: http://www.sfep.org.uk/directory/directory.asp
I just published my fourth ebook novel recently and I've used Ebook Launch every time with very satisfactory results. They always promptly turn around the cover and manuscript formatting - and as an added bonus, they always promptly and happily answer even the stupidest questions I come up with. Adrian is very easy to work with and Dane has repeatedly come up with cover ideas when I was fairly sure that it couldn't be done.
I’m a first time writer. Today I’m about 60% done with a “novel” (a thinly disguised autobiographical account of finding romance and starting a family during the Viet Nam war). I believe that hiring a developmental editor at this time would help me complete the work in a better ‘voice’, ultimately saving time and money. The alternative would be to finish the work as this column advises before submitting for edit.
Moreover, the casual distinction between a (developmental) “editor” and a “copyeditor” can be a bit simplistic, particularly in a self-publication or even vanity-publishing context. A self-published author may barely have the budget to hire one editor, so that editor needs to be able and willing to blur the lines between developmental editing and copyediting. The editor must also be accustomed to working with authors of a variety of strengths and weaknesses, including many whose work would not, in fact, have been accepted by a commercial publishing house in its current form. I have come to take great satisfaction in taking a new or newish author by the hand and helping them find ways of making their work the best it can be. Of necessity, this must include line-by-line correction of grammar and style (often a surprisingly great amount of such correction), but can rarely be limited to that.
Regarding your last question, I know of no editor who gives a money-back guarantee for occasional errors that happen to slip through or for a different opinion by a later editor. I’m afraid such things are just the nature of the publishing beast. But by having a shorter portion edited first, you will get a decent feel for whether someone is the right editor for you, and will be able to be confident in his or her work on your entire book.