From J A Konrath:
Now you can certainly pay people to help you publish. Freelancers such as editors, cover artists, book formatters, proofreaders, and so on.
But when you hire a freelancer to assist you, you keep your rights.
That's very important.
When you write something, you own the copyright. That's automatic, even if you don't register with the copyright office.
Copyright means exactly that; you have the right to copy it, to distribute it, to give it away, to sell it. You own those rights.
But if you pay someone to publish you, you GIVE THEM YOUR RIGHTS.
NEVER GIVE ANYONE YOUR RIGHTS.