What to ask before saying "yes"

I do a lot of writing for corporate clients and ad agencies. And while most of the time the assignments are clearly defined in terms of what I have to do, when I have to do it and how much I am getting paid, sometimes there are key pieces of information that are missing.

And I have learned (from bitter experience) that I need to get all the details nailed down before agreeing to the job. Otherwise, things can get very dicey indeed.

So for those of you who aren't sure what to ask (and especially...