In most situations nothing beats natural light. This morning I was playing with my daughter in front of our large picture window when I noticed the light fall-off on the side of her face as she gazed outside. I knew just looking at her if I used a high shutter speed I could drop the background to a solid black even though the room was fully lit. It's actually a gloomy day outside which is perfect - clouds create the perfect diffuser, softening the light and removing all the harsh shadows that are present on a sunny day.
I propped her up between my knees as she braced herself on the back of the couch. Leaning back I snapped a few photos, as she looked around. Composition was a little difficult because just to the left of the frame are the white window blinds which completely throws off the image. I cropped them out in camera, while keeping her to the right side. After a few test shots I landed on 1/250th of a second which was enough to drop the background completely black. I bumped the shadows just a touch to make it a bit more dramatic, adjusted the color temperature, sharpened up her eye and that was it.
For adult portraits and other situations I do like using off-camera flash, but for simple, up close headshots and portraits, I still absolutely love natural light. During the summer I try to shoot during the early morning and evening to avoid harsh light, however when its cloudy thats the perfect time to shoot all day long. So don't be dissapointed on gloomy days, grab your camera and make something special.