Originally Posted by
tirediron
A lot has to do with what kind of a backdrop it is; soft cloth, paper, rigid, etc...
Generally you're going to want to make sure it's smooth (unless it's one that's very specifically meant to be wrinkled like a set of pulled-back window drapes) and that it curves gently from the vertical to the horizontal when it meets the floor. Make sure that your subjects aren't too close; a lot of people have a tendancy to jam the subject right against the backdrop. Make sure there's a couple of feet of separation, and spend lots of time playing with lighting. Your on-camera flash isn't really going to cut it, but you can do a pretty good ad-hoc job with work lights, lamps and paper reflectors.
Let us know how it works out.