So this is a pic of my normal photo set up. It's about as bare bones as you can get- a couple of halogen lamps, a couple of pieces of white paper and a cheap digital camera and you're good to go. The important thing to keep in mind is that the back of the paper should curve up into the vertical section, not be creased; this gives the illusion of a large white room and causes the light to reflect in more naturally. Time it takes to set up? 15 seconds. The models hold the paper in place and you can maneuver your camera so that all that you can see is the model and the white paper.
Of course there are some problems with this set up, mostly that the lighting isn't exactly the best. There are occasionally shadows or the lighting doesn't make the model pop as much as you might want. In that case I turn to my friend GIMP and his tools Brightness/Contrast.
GIMP is a free photo-editing software that, if you don't own, you should download. It's a great way to quickly crop photos and touch them up a bit. If I don't feel that a particular shot had enough light I'll boot up GIMP and go to Colors -> Adjust Brightness and Contrast. Moving them both up together keeps the quality of the coloring consistent, but try to keep to around 30% increase, increasing or decreasing depending on your own personal taste. You can even get rid of blurriness to some degree by using the Sharpen tool, always useful when you just don't want to go back and set up another shot.
I hope this was helpful. There are a lot of better and more elaborate set ups that you can use, but if you're like me and either don't want to build a photo box or want to be able to take a shot no matter where in your home you happen to be, the cheap pieces-of-paper approach can definitely be useful. Some ways to improve this technique include using larger pieces of paper, having a cyan/magenta/yellow pattern in the background, and getting more lamps positioned at different angles.
As always, post your comments and questions or contact me directly at firstname.lastname@example.org.