I haven't posted much lately warning writers and wanna-be writers how to avoid being cheated or abused but there's a lot of that on this site if you browse back over the many years of its existence. Here's an article in the Writers Guild's magazines that may alert you to a few more things to watch out for.
And I'll add one more: The phrase "knock out a few pages." That's a euphemism for "Do writing work for which you should be paid but don't expect to be paid."