If using a light/reflective backdrop (e.g. mirrors or snow) don't use a manual mode. Set the exposure so that the camera doesn't "dim" or auto-adjust the exposure.
If taking an outdoor picture, directional light is best, making a dawn or dusk lighting the best situation.
If taking a picture near lights of any kind, arrange a good photograph of the lights. Then, place the occupants/subject into the picture to fill where it should be.
Only use a flash around noon - at this time, the flash will soften the hard light, but at other times, it will flatten the photograph.
Eye lines should be approximately a third down from the top of the picture.
