For me, the most important warning sign to look out for is the percentage of and basis of penalties applied to writer earnings. Once the company places too much emphasis on the penalties of a writer, you can bet that they will always penalize your salary for any trumped up charges, whether client or QAD related. Read the fine print. The companies that plan to cheat the writers will always bury the penalties reference in a part of the website that the applicant writer would never consider looking into. If you cannot find it, ask their writer representative outright. The mor evasive their response and explanation, the more you should not work with the company.
Opinions are that of the author's alone based on an individual capacity. Opinions are provided "as is" and are not error-free.