One of the most helpful and least expensive tools that any photographer should have is a bounce reflector. Every studio, whether it be home based or professional high end setup should have two or three reflectors of a decent size. The problem as always is money, and shelling out 40$ to 80$ of your hard earned money on them.
Fortunately there are multiple ways around this little issue. This setup requires you to drive to two different stores, so prepare yourself first. Grab some driving food, I highly recommend cheese curls or ho ho's. A word of caution though, cheese curls while driving can be a dangerous situation due to cheese slippage on the wheel. Once you've got some food in hand, be sure to grab a drink to go with your food because theres nothing worse then dry mouth at 60mph.
Venture out into the wide world and point your vehicle to your nearest appliance store, and not the big chain stores like Lowes, or Best Buy. Pick a mom and pop appliance store that has a local history and is hopefully still run by the original owners. Once you've found your store go there and ask to speak with the owner. Tell the owner that you are starting up you're own home business and appeal to his entrepreneur side and politely ask if they have any refrigerator boxes out back that they are just going to throw out. If they have a couple, ask if you can have them. Most businesses will be cool with this, but if they aren't just say thank you and move on to the next store.
Once you've managed to score some refrigerator boxes try not to bend them if possible. So if you have a truck that would work best. We'll need the rigidity of the cardboard to stay intact as much as possible. So slide the boxes into your hoopdy and point it towards the next stop, the dollar store. At this point in the shopping plan, you should have spent exactly zero dollars.
Once you're at the dollar store, feel free to browse through the over abundance of poorly made plastic lawn ornaments and batteries that are 4$ a box - yah go figure that one out. Anyway, root around for a bit and find the white poster board. Most dollar stores sell poster board for 1$ a sheet, and they are usually 36" by 48" or around there. Grab ten sheets, or less if you want to do some math and figure out how much will cover the sheet of cardboard in your hoopdy. I just buy ten because you can always use poster board for a lot of different stuff.
Once you've got the cardboard boxes and poster board head back to the bat cave and park the hoopdy. Run inside like a small child at Christmas and get a razor blade or something sharp to cut the boxes with. You want to cut the boxes along the folds, depending on the size of room you are looking to put the reflector in. I normally just use one side of the box, but you can keep a bend in the middle and use two sides for a huge bendable reflector if you want.
When you've got a single side cut out, get some glue or tape - i recommend tape. Cut the poster board so that it fits side to side on the cardboard. You want to cut enough poster board so that you can cover the cardboard box side completely in white. But don't overlap the poster board, make sure its flat. Use the tape to tape the corners down, and back middle, you don't want the poster board to bow out. Once you've got the poster board all taped down and flat on the cardboard you've officially made a cheap bounce reflector for the low low price of 10$.
Placing it in a shot is just as easy. Put your subject in the middle of your space, and place the camera at a straight on position facing the model. Grab you're light source and put it on one side of the model, then take the newly built reflector on the opposite side close to the model but out of the cameras view. This will provide you with a nice soft bounce light on the shadow side of you're subject. Giving the shot this little extra illumination, especially on the face creates a much softer portrait look.
Just remember to move the newly built reflector before the wife or girlfriend gets home and sees all the carnage you've caused to the house!