No, but I am super curious. How did you get into it?
I'll provide a TLDR at the bottom cause it's kinda (understatement) a long story:
Back in late 2014 I was working on getting my Fiance (Wife now), who lived in India at the time, over to the U.S. through a K-1 Fiance Visa. Needing extra money as my screenwriting career hadn't yet taken off (still hasn't stupid Hollywood and their pension for remakes and sequels) I turned to freelancing.
At the time I set up an account on Elance.com, although they've since shutdown and merged with Upwork.com. It was a fairly smooth process, involved making a profile, providing samples of my work and setting a price. It helped, I think, that I had a contest win under my belt: my script Valdfellgar, about a time-traveling Vampire hunter slaughtering Vampires hidden throughout time to avert his time's apocalypse, won third place in the Storypros screenwriting contest:
http://www.storypros.com/excerpts/VALDFELLGAR by Thomas Daniell.pdf
The soul crushing aspect of freelancing like this is, especially when you're starting out, you're basically 10 dollars an hour tier, even if writing is hard work.
My first job wasn't novel ghostwriting on there, that didn't come till later. The first job I got chosen for was to help some small time Australian Producer take a thriller novel called Dark Horse and adapt it into a screenplay. The book was about some woman who was losing her ranch thanks to a divorce and took one last trip up the nearby mountain where she became trapped thanks to a horrid storm and was forced to take shelter in the mountain's lone cabin. There she meets a mysterious man etc. etc. might be going crazy, etc. etc.
Initially the job was billed as me having to eventually write the screenplay after helping to summarize the novels contents. However, the project was supposedly picked up by some big producer back here in the U.S. (although if I recall nothing ever came of his involvement with this woman.) Throughout the project he spit-balled ideas with me to bring about a new ending (he didn't enjoy the book's 'third act'.) It quickly became apparent that he wasn't really interested in my ideas, which I did offer, but rather wanted me to tell him how genius his ideas were (They weren't.) Either way I was happy to be making some money from my writing. But as that producer came into play he decided to set aside the project and reserve it for her when she became ready.
Instead he shunted me off to two other novels: Sweet Damage, a story about a supremely anti-social girl plagued by the deaths of her parents and her involvement with a young man who moves in as her tenant. And another book, the name's escaping me, about a woman and her girlfriends getting a mother's weekend away and becoming victims of two thugs who beat them and tied them up while searching their vacation house for something they buried years ago. In both cases I summarized the books for him, got paid, but was transferred onto the next before I could actually flex my writing skills (There was always an excuse waiting 'oops I didn't have the rights squared away yet' or whatever). I think he really just wanted someone to do the busy work for him, which I was fine with, I just wish he'd been upfront about it.
Eventually this guy disappeared, I assume he either got tired of my results or become flustered with his efforts on Dark Horse, or maybe I summarized all the books he had rights to. After sometime I found a second job, this time for a Texas based individual who supposedly already had an agent for his sci-fi/political drama TV series pilot. If I recall correctly he had a half-written series bible that detailed certain characters far more than others (the women were especially underwritten. I believe one character's entire purpose and focus was on becoming a mother.)
That one took a lot of effort. I had to flesh out characters he hadn't bothered to do anything with, yet were important to the story. Then I had to adapt and dramatize his outline, which I believe changed several times before I was even done with the first draft, as he kept adding in content and overestimated how much he could fit into a 60 minute TV pilot. This job was more frustrating as the notes he gave were often grammatically incorrect, making it difficult to understand what he wanted. Eventually he went away happy with the script, but then came back with notes he wanted me to add in that he'd scribbled onto a print out copy and then scanned back in. Unfortunately his handwriting was illegible in numerous places, making it difficult to understand what he actually wanted me to change or rework.
Getting away from that job I'd managed to build up enough of a reputation on the website to update my pricing a little and, with completed jobs under my belt, appear as a worthy investment. Screenwriting gigs are difficult to find on there. Either it's work like I described above, or people asking you to help them write their screenplay and then network for them (which is, like, if I had the networking ability would I really be doing any of this freelance work?)
So I turned my attention to the novel/book writing. It took a bit but I lucked into this guy who wrote numerous Sci-fi series self-published books on Amazon. He gave me a writing sample test, asking me to write 5,000 words on some one off idea and when I produced favorable results he assigned me to a new sci-fi book series he was working on.
He didn't actually show me his other work, I think it was supposed to be a secret that he turned to Ghostwriters much of the time. He'd fabricated his own writing persona, with a fake name and a fake life in Florida (he lived somewhere else.) I basically connected the dots looking at his past Elance job listings, which either called for work on a few different novels, or asked for voice actors to create audio book versions of his older work. The reviews were often middling for his stuff. Complaints about shallow characters, poorly thought out concepts, a bizarre obsession with popcorn humor, etc.
Anyway I took the job and began learning that there was way more to this work than met the eye. For starters, he'd neglected to mention he'd already had a previous writer attempt to adapt his notes. This guy had apparently done about four chapters and called it quits. So at first I was working from this guy's efforts, which were very middle of the road. I added a lot of personality, character, and my own special touches with my style. He loved it, was actually super thrilled.
But once I got further in I started having to work with his notes instead of the previous writer's copy. That was harder, as his ideas were less fleshed out and it required more work to adapt. Then I noticed something. After a few more chapters I discovered that the writing style changed again. Finally he came clean and admitted I was actually the third writer to work for him on this project. From there things got completed and while it was enlightening, fun at times, and even ego boosting-- there was this inescapable frustration/depression of "I'm putting in all this effort, injecting ideas that help to round out this work, even in someways make it my own, and my name won't be on it in the end."
Eventually I finished his book, it took a total of three months, one of those spent almost entirely rewriting his original outline, which he approved of, once it became clear his notes were too jumbled. (He'd apparently cut multiple chapters into multiple smaller chapters and reordered them, which meant nothing made sense.) By the end of it he decided he wanted to rework the book further, but I was preparing to head out to India to help my Fiance with her application, and by this point I'd decided Ghostwriting wasn't for me. I need some form of recognition for my effort. We parted on good terms though, and he checked in with me later in the year to ask if I'd reconsider working for him (I guess he'd been that happy with my efforts) and even wished me the best when I told him I was working on my own novel. Really buttered me up to saying I'd go far with my talent.
TLDR Version:
Go to a place like Elance.com (Now Upwork.com) make a profile, put some samples of your writing work or ability on there. Mention any contests or awards if possible, set a price for yourself and begin applying for jobs posted on the website. As you become 'known' you can increase your price and even opt in to new jobs for clients less willing to work with newbies.
Don't expect your name to show up on the finished product, or for there to always be one as you're often initially working with amateurs themselves. Supposedly, once you get good enough, you can create your own website and market yourself to bigger and better clients (I know Carrie Fisher, after Star Wars, made a huge killing as a Ghostwriter in Hollywood/Script doctor.)