One of the things you may wish to do this festive season is use off-camera TTL flash.
I.e. holding the camera in your right hand and the flash elsewhere – for instance in your left hand (or your other fight hand if you have two – well spotted, Mike).
In any case: away from the camera – this is key to good pictures.
All brands of camera allow this, and if you have a Nikon, or a Canon 7D or 60D, you do not even need additional hardware: just your flash and your camera, with its popup.
The popup (or on other camera, the on-camera flash) now sends commands to the other flash. So you can light a subject – like the student in Thursday’s Flash class – from one side, in this case with a flash in an umbrella on our right side, with a reflector on our left:

Off-camera flash using TTL
Much better than straight flash!
You can even use several flashes, divided into groups. In the next shot, we have an additional flash on our left, rather than a reflector. That flash has a red gel (one of the Honl Photo gels) on it, to see clearly which light is doing what work:

Off-camera flashes, using TTL
But what you must remember is this:
Disable the on-camera flash.
That is, the pop-up or 580EX/SB900 on your camera still sends its commands to the other flashes, but when the actual photo is beingtaken, it does not flash.
If you forget to disable it, it will fire. And then you get this unfortunate effect:

On-and Off-camera flashes, using TTL
Deer in the headlights. Harshness. Shadows. Brrr: baaad.
So your tip: use off-camera flash, and disable the main flash from firing actual flashes. The camera menu (or the flash on your camera) has functions for this.
If you want to learn this and many other techniques before the holiday, take the advanced flash course in Mono (see http://www.cameratraining.ca) next week. Else, take a course with me or at Henry’s early in the year. It is worth learning flash!