Get the flash off the camera

Unless you walk around with a miner’s helmet all day, you don’t usually see the world lit with a light pointing directly at whatever is in front of you but that is the world we photograph when using the built in flash on a camera (or a flash in the hotshoe).

Particularly when photographing people, this is not a very flattering way to light your photos so if possible get your flash away from the top of the camera. How far away from the camera you can get it will depend on the situation. There are rigs you can attach to your camera to move the flash just a few inches away from the camera (it’s enough to make a difference) which is useful if you still need to carry your light around with you.
Off camera flash
If you are going to set up your flash in one place, a favourite option is to use a wireless flash trigger (such as Pocket Wizards (US / UK), the Elinchrom Skyports or the cheap, cheerful and sometimes unreliable Cactus triggers (US / UK)) to set off the flash from the other side of the room. This way you can move to where you want to be to take the photo and have an assistant (or light stand) hold the flash and point it at your subject from a different angle.

Off camera flash is a huge subject in its own right. If you’re interested in learning (a lot) more, the place to go is the Strobist blog and get a copy of The Hot Shoe Diaries (US / UK).

Bounce and diffuse

Like the previous tip, this really applies to flash photography in general rather than specifically low-light situations. In fact when light is at a premium, you don’t want to spread it too thinly by diffusing it and bouncing it off surfaces. That said, a direct hit from a flash gun can be quite unflattering so if you’re going for a natural rather than a spotlight look, bouncing or diffusing the light from the flash can help.
lightsphere
In low-light try to bounce of a surface that’s near both your flash and your subject. Light intensity and distance are related by an inverse square law which means halving the distance between the light source and the subject quadruples the light intensity. Moving yourself and/or your subject a bit closer to the surface you’re bouncing off can make a big difference.

If you’re using a diffuser, make sure you get the most from it. Some diffusers (such as the popular Lightsphere shown in the picture to the right) will direct light away from your subject as well as towards it so consider whether you might modify the diffuser (with some aluminium foil) to redirect all the light towards your subject (but still diffuse it of course). The Lightsphere has the advantage that it diffuses the light that goes towards the subject but also allows some light to go up and bounce off the ceiling which significantly softens shadows.

Gel your flash to match available light

Our eyes are pretty good at adjusting to different lighting conditions but your camera doesn’t know how to adjust to the difference in colour between different light sources. If you’re going to be taking photographs with a mixture of flash and other light sources, you might want to consider changing the colour of the light from your flash by using lighting gels.
Flash gels
If you can match the colour of the light from your flash to the colour of the light from the other light sources then the resulting photo will have consistent colour and you can then make white balance adjustments or corrections in camera (or in RAW processing later) to account for the colour cast from the lights. This is much easier if all your lights require the same correction.

To get the light from your flash to look more like the light from a normal bulb, gel your flash using a CTO (colour temperature orange) filter. Photogels in the US or FlashGels in the UK sell gels pre-cut for use on standard small flash units.

   

Off-camera flash image by MarvinKuo. Lightsphere by tinou bao. Flash gels by Mhogan35.