Reflectors are great, use them indoors and out. If you need something in a pinch, look around, find something white or silver and flat. You can run out to the dollar store or a local frame shop for a piece of foam core. A 3 foot by 2 foot piece works very well for head shots. If you need something for full length the frame shop carries much larger pieces, 5 to 6 feet by about 3 feet. What I did with my large piece is measure dead center and scored it right down with a box cutter. DO NOT cut all the way through, this will allow you to fold it a bit so it stands on it’s own. Now I have a 5 foot white screen that can stand on it’s own and foam core is very light weight, easy to tip if needed and easy to carry around.
Another quick way to make a reflector is take a piece of cardboard and cover it with aluminum foil, shiny side out, tape it down the back. Or use a silver windshield protector.
A white reflector is an all purpose fix to help lighten shadows.
A silver reflector will also lighten shadows but it will also add contrast.
A gold reflector will also lighten shadows, but will add a golden tone.
A black reflector will cut light where you don’t want it.