Yes, this has become my post-retirement career. It is relatively new to me so I am looking for constructive input and ways to build on it and improve it. I only email authors if I've read their entire book and I enjoyed it and want to read more of their work, especially those that are a series and I'd like to continue through the remainder of the series. That would be the first thing I let them know, along the lines of "I just finished your book and enjoyed your characters Dick and Jane and especially Spot. In reading I noticed: and then I'd give 2-3-4 examples.
I will reread the comments here and appreciate them. I couldn't think of any other means of contacting and interacting with authors so I tried the emails. I look forward to any further constructive comments that may help me figure this all out.
If you were looking for advice on how to start the career, you should do some research. You could have asked here for other editors' opinions or experiences. You could start a thread about your business, as many others have done. Starting out emailing authors about what they've done wrong -- whether you're correct or not -- isn't how it's done, no matter how much you say you enjoyed the work.
You've been a member since 2008, so I would imagine you've seen the threads where the emailing offering editing services were discussed. People used to get them from Goodreads, too. It's been a while since these threads were posted, but I recall them being kind of long.
I see you've removed the link in your signature, but I followed it when I first read the OP and it took me to a page where you advertised your services. This is how I confirmed my suspicions from the way the OP was worded that it wasn't about how writers don't want to fix their errors, but rather a round-about offering of editing services.
You'll find that we don't appreciate Warrior Forum-type businesses or practices here. We tend to be skeptical and not afraid to express our opinions. It's the kboards way and what makes the WC one of the best writer forums you can find.
That said, start a business thread, build a website, figure out how to promote your business and where. Ask other editors here for their advice. You'll find we really want to help. Good luck.