Since I mentioned them, you can probably tell that these requirements are not often followed, though they should be a given. I have found that out the hard way!
What I do take as a given is getting paid for my work. How much? That is hard to say, and depends, among other things, on the level of sophistication the job demands, or on whether conceptional work is required. I will usually work out a binding cost estimate for the job at hand. In cases where a flat fee does not seem to be called for, I apply an hourly rate. For copywriting services, the rate starts at 95 euros.